Propose CI infrastructures in github action

[laserprec]

Description

To improve developer experience working with this repo, we will begin migrating our DevOps pipelines into Github Action, along with consolidating documentations and leveraging popular DevOps tools like tox and flake8. This will be a sequence of updates to our DevOps infrastructures:

1. Propose and draft the CI pipeline in Github Action <---- (Current PR)
2. Optimize build time for unit tests
3. Enforce flake8 (coding style checks) on the build and clean up coding styles to pass flake8 checks
4. Setup self-hosted machines to run our GPU workloads
5. Run tests on the appropriate dependency subsets
6. Create feature parity with the existing CI pipelines (pr-gates & night-build)
7. Deprecate CI pipelines in ADO and switch to Github Actions

In THIS PR

we have the following changes:

1. Add a draft of PR-gate implemented in GitHub Action executing test suite in parallel ([FEATURE] Move the tests to hosted machines #1460)

   • Status badge to the CI pipeline:
     

2. Add __init__.py to subfolders of tests (resolves issue [BUG] testing within vscode #1395)

3. Deprecate .pytest.ini in favor of tox.ini and ensure repo is tox-runnable.

   • Tox is great for establishing parity between local and build environment (less "this works locally but not in build ")
   • For example: you can just run tox -- tests/unit -m "not spark and not notebooks" to run cpu tests after installation.
   • For more convincing words on tox, please read this 😃

Related Issues

1. [FEATURE] Move the tests to hosted machines #1460
2. [BUG] testing within vscode #1395

Checklist:

• I have followed the contribution guidelines and code style for this project.
• I have added tests covering my contributions.
• I have updated the documentation accordingly.
• This PR is being made to staging branch and not to main branch.

[gramhagen]

a few questions, and small typo suggestion

[gramhagen]

lgtm

[codecov-commenter]

Codecov Report

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