[config] Add 'interface transceiver' subgroup with 'lpmode' and 'reset' subcommands

[jleveque]

Add 'transceiver' subgroup with 'lpmode' and 'reset' subcommands to 'config interface' group, wrapping sfputil commands.

New command examples:

user@sonic~$ sudo config interface transceiver --help
Usage: config interface transceiver [OPTIONS] COMMAND [ARGS]...

  SFP transceiver configuration

Options:
  -?, -h, --help  Show this message and exit.

Commands:
  lpmode  Enable/disable low-power mode for transceiver
  reset   Reset transceiver

user@sonic~$ sudo config interface transceiver lpmode --help          
Usage: config interface transceiver lpmode [OPTIONS] <interface_name>
                                           (enable|disable)

  Enable/disable low-power mode for SFP transceiver module

Options:
  -?, -h, --help  Show this message and exit.

user@sonic~$ sudo config interface transceiver lpmode Ethernet0 enable
Enabling low-power mode for port Ethernet0...  OK

user@sonic~$ sudo config interface transceiver lpmode Ethernet0 disable
Disabling low-power mode for port Ethernet0...  OK

user@sonic~$ sudo config interface transceiver reset --help
Usage: config interface transceiver reset [OPTIONS] <interface_name>

  Reset SFP transceiver module

Options:
  -?, -h, --help  Show this message and exit.

user@sonic~$ sudo config interface transceiver reset Ethernet0
Resetting port Ethernet0...  OK

[abdosi]

@jleveque Cherry-pick into 201911 seems to have issue with the change @interface.group(cls=AbbreviationGroup)

I think we ned some other PR's also to go with this one to complete the support of this cls=AbbreviationGroup

For time being i have reverted this PR form 201911.

admin@str-dx010-acs-1:/$ sudo warm-reboot -vvv
Traceback (most recent call last):
File "/usr/bin/config", line 8, in
from config.main import config
File "/usr/lib/python2.7/dist-packages/config/main.py", line 1839, in
@interface.group(cls=AbbreviationGroup)
NameError: name 'AbbreviationGroup' is not defined
Thu May 21 02:40:00 UTC 2020 warm-reboot failure (1) cleanup ...
Traceback (most recent call last):
File "/usr/bin/config", line 8, in
from config.main import config
File "/usr/lib/python2.7/dist-packages/config/main.py", line 1839, in
@interface.group(cls=AbbreviationGroup)
NameError: name 'AbbreviationGroup' is not defined
Thu May 21 02:40:01 UTC 2020 Cancel warm-reboot: code (1)
admin@str-dx010-acs-1:/$

[jleveque]

@abdosi: This PR is dependent upon #893. I just added the "Request for 201911 branch" label to that PR. Please see if it will cherry-pick cleanly. If not, we will need to create a separate PR.