Add `automatically-request-copilot-review.yaml` workflow

[ChrisCarini]

Summary

This PR adds a GitHub Actions workflow to automatically request Copilot code reviews for pull requests in linkedin/Liger-Kernel.

Changes

• Added .github/workflows/automatically-request-copilot-review.yaml
• The workflow will automatically request Copilot reviews on all PRs

⚠️ ⚠️ ⚠️ ACTION REQUIRED ⚠️ ⚠️ ⚠️

You still need to create a GitHub Personal Access Token (PAT) and add it to the repository secrets for this GitHub repository!

1. Click here to create a classic GitHub PAT with the correct scopes (repo)
   • Note: You will have to select an Expiration value you feel is reasonable from a usability + security perspective given the necessary scopes and usage.
   • Note2: Creating a fine-grained PAT with the permission(s) documented https://github.com/ChrisCarini/gh-copilot-review?tab=readme-ov-file#token-permissions is a better option, from a security standpoint.
2. You will need to set a repository secret named GH_TOKEN_COPILOT_REVIEW for all the desired repositories
3. Once the secret named GH_TOKEN_COPILOT_REVIEW is added, please merge in the PR after getting the necessary approval(s).

How it works

When a pull request is opened or updated in the linkedin/Liger-Kernel product, this workflow will:

1. Checkout the repository
2. Automatically request a Copilot review using the configured token
   • Note: Whoever created the PAT will show up as the one requesting the review from Copilot.