Feat: Add workflow to automatically add assignee and add reviewers in the PRs

[Saphall]

Summary

Add GitHub workflow to automatically add assignees and reviewers in the PR.

When the reviewer is automatically added, he/she will be notified instantly after any PRs are opened/ready_for_review.

Pull request type

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Documentation content changes
• Other (please describe): GitHub Workflow to auto add assignees and reviewers in the PRs

What is the current behaviour?

Issue Number: N/A

What is the current behaviour?

• When any PR is opened, sumanashrestha is automatically added to the reviewer. This way - whenever any PR is opened, the reviewer is notified to review the changes. The reviewer list can be updated later, if required, to add more reviewers who are responsible to review the changes.

• The author (one opening the PR) is automatically added as the assignee.
  

Checklist

Please review and complete the following checklist before submitting your pull request:

• I have tested the changes locally and they work as intended.
• I have provided a detailed description of the changes made.
• I have reviewed the formatting and ensured it follows the project's style guidelines.
• I have assigned the appropriate labels to the pull request.
• I have added necessary documentation or updated existing documentation for the changes made.
• I have addressed code review feedback and resolved any conflicts with the main branch.

Other information

• [BEFORE] : the reviewer and assignee sections are empty on PR creation.
  

• [AFTER]: the reviewer and assignee sections are automatically assigned to respective individuals.
  e.g.
  

PS: The reviewer is automatically added to PRs once this workflow is merged.