[FEAT] github greetings automations

[urs-santoshh]

Summary

This PR add automations for greeting message for PR and Issue

Pull request type

Please tick the type of change your PR introduces:

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no API changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

Checklist

• [ ] 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.
• [x] 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.