[IPv6 only]Fixture to convert/revert the mgmt-ip to IPv6 olny, enhance connection plugin

[yejianquan]

Description of PR

1. Add a fixture to convert the DUT to IPv6 only(only mgmt-ip)
2. Enhance the connection plugin to re-connect with the IPv6 address if the IPv4 address is unavailable
3. Add a new test module with examples to test the IPv6-only scenario.

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 201911
• 202012
• 202205
• 202305
• 202311

Approach

What is the motivation for this PR?

Support test mgmt-ip IPv6 only scenario.

How did you do it?

Remove the IPv4 mgmt address before the test module starts, and restore after the test module is finished.
Enhance the connection plugging to first connect with the IPv4 address, and retry with the IPv6 address if IPv4 is unavailable.
Add a new test module with examples to test the IPv6-only scenario.

How did you verify/test it?

Run on physical testbeds, with dual-stack mgmt-ip addresses testbed and only with IPv6/IPv4 mgmt-ip address testbed.

================================================================================================================== test session starts ==================================================================================================================

ip/test_mgmt_ipv6_only.py::test_bgp_facts[-None] PASSED [ 25%]
ip/test_mgmt_ipv6_only.py::test_bgp_facts_ipv6_only[-None] PASSED [ 50%]
ip/test_mgmt_ipv6_only.py::test_show_features[-4] PASSED [ 75%]
ip/test_mgmt_ipv6_only.py::test_show_features_ipv6_only[-4] PASSED [100%]

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
--------------------------------------------------------------------------------------------- generated xml file: /var/src/sonic-mgmt-int/tests/logs/tr.xml ---------------------------------------------------------------------------------------------
======================================================================================================= 4 passed, 3 warnings in 741.52s (0:12:21) =======================================================================================================
INFO:root:Can not get Allure report URL. Please check logs
jianquanye@sonic-mgmt-jianquanye:/var/src/sonic-mgmt-int/tests$

Any platform specific information?

No.

Supported testbed topology if it's a new test case?

All topologies.

Documentation

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Failed
- hook id: end-of-file-fixer
- exit code: 1
- files were modified by this hook

Fixing tests/common/devices/duthosts.py
Fixing tests/ip/test_mgmt_ipv6_only.py

check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

ansible/plugins/connection/multi_passwd_ssh.py:66:121: E501 line too long (903 > 120 characters)
tests/common/fixtures/duthost_utils.py:639:44: E127 continuation line over-indented for visual indent
tests/common/fixtures/duthost_utils.py:641:44: E127 continuation line over-indented for visual indent
tests/common/fixtures/duthost_utils.py:644:121: E501 line too long (129 > 120 characters)
...
[truncated extra lines, please run pre-commit locally to view full check results]

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Failed
- hook id: end-of-file-fixer
- exit code: 1
- files were modified by this hook

Fixing tests/common/devices/duthosts.py
Fixing tests/ip/test_mgmt_ipv6_only.py

check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/ip/test_mgmt_ipv6_only.py:5:1: F401 'tests.common.helpers.assertions.pytest_assert' imported but unused
tests/ip/test_mgmt_ipv6_only.py:15:30: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 4
tests/ip/test_mgmt_ipv6_only.py:21:63: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 4
...
[truncated extra lines, please run pre-commit locally to view full check results]

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Failed
- hook id: end-of-file-fixer
- exit code: 1
- files were modified by this hook

Fixing tests/common/devices/duthosts.py

check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/ip/test_mgmt_ipv6_only.py:13:30: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 3
tests/ip/test_mgmt_ipv6_only.py:49:63: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 3

flake8...............................................(no files to check)Skipped
check conditional mark sort..........................(no files to check)Skipped

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[yejianquan]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Failed
- hook id: end-of-file-fixer
- exit code: 1
- files were modified by this hook

Fixing tests/common/devices/duthosts.py

check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/ip/test_mgmt_ipv6_only.py:13:30: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 3
tests/ip/test_mgmt_ipv6_only.py:49:63: F811 redefinition of unused 'convert_and_restore_config_db_to_ipv6_only' from line 3

flake8...............................................(no files to check)Skipped
check conditional mark sort..........................(no files to check)Skipped

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[wangxin]

PR title is so long. Can you make the title shorter?

[mssonicbld]

@yejianquan PR conflicts with 202305 branch

[mssonicbld]

@yejianquan PR conflicts with 202311 branch

[mssonicbld]

Cherry-pick PR to 202311: #11983

[mssonicbld]

Cherry-pick PR to 202305: #11984