Add Repo Automator GitHub Action

[iamdharmesh]

Description of the Change

PR adds Repo Automator GitHub Action to automate common repo operations like validate PR, Auto request review, Auto-assign PR, Auto Add milestone, Auto-label for merge conflicts, etc...

How to test the Change

Verify GH action run on this and it works properly.

Changelog Entry

Added - Repo Automator GitHub Action

Credits

Props @iamdharmesh

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests pass.