Build: Add GitHub Actions for PR labeling and automatic title prefixing

[skytin1004]

Purpose

I've added two GitHub Actions: one for labeling pull requests based on file changes, and another for automatically adding a title prefix to issues or PRs based on the label applied.

Description

• Added a GitHub Action for labeling pull requests based on modified paths (labeler-pr.yml).
• Added a GitHub Action for automatically adding a title prefix to issues or pull requests when specific labels are applied (label-title-prefix.yml).
• The title prefixes are dynamically generated based on the applied label (e.g., "Docs", "Build", "Translator").

Related Issue

No related issues.

Does this introduce a breaking change?

When developers merge from main and run the server, azd up, or azd deploy, will this produce an error?
If you're not sure, try it out on an old environment.

• Yes
• No

Type of change

• Bugfix
• Feature
• Code style update (e.g., formatting, local variables)
• Refactoring (no functional or API changes)
• Documentation content changes
• Other... Please describe: GitHub Actions for PR labeling and title prefixing

Checklist

Before submitting your pull request, please confirm the following:

• I have thoroughly tested my changes: I confirm that I have run the code and manually tested all affected areas.
• All existing tests pass: I have run all tests and confirmed that nothing is broken.
• I have added new tests (if applicable): I have written tests that cover the new functionality introduced by my code changes.
• I have followed the Co-op Translators coding conventions: My code adheres to the style guide and coding conventions outlined in the repository.
• I have documented my changes (if applicable): I have updated the documentation to reflect the changes where necessary.

Additional context

These new GitHub Actions will help streamline the pull request process and enforce a more structured approach to labeling and titling pull requests and issues.

[skytin1004]

I have reviewed the changes and everything looks good.