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, Auto-Sync PR branch, etc...

Alternate Designs

Possible Drawbacks

Verification Process

Verify GH action run on this and it works properly.

Checklist:

• [x] I have read the CONTRIBUTING document.
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests passed.

Changelog Entry

Added - Repo Automator GitHub Action

Credits

Props @iamdharmesh