Added greeting workflow

[naman9271]

Fixes: #1246

This pull request introduces a new GitHub Actions workflow to welcome and guide first-time contributors to the project. The workflow automatically comments on new issues and pull requests, providing helpful resources and instructions.

Contributor experience improvements:

• Added a .github/workflows/greetings.yml workflow that uses actions/first-interaction@v1 to greet first-time contributors on issues and pull requests, including tailored welcome messages and links to documentation, contributing guidelines, and code of conduct.

[naman9271]

Hi @joaquinvanschoren , @janvanrijn please review when you get a chance - thanks