Doc blocks and minor code improvements for `src/Tribe/Changelog_Reader.php`

[IanDelMar]

🎫 Ticket

N/A

🗒️ Description

This PR introduces the following enhancements:

• Documentation Improvements: Added comprehensive doc blocks for better code understanding and maintenance.
• Type Safety: Implemented type hints and declarations to ensure type safety.
• Code Quality Enhancements:
  • Strict Comparisons: Replaced loose comparisons with strict comparisons to enhance reliability.
  • Elimination of Magic Constants: Replaced magic constants with meaningful constants for better readability and maintainability.
  • Type Narrowing: Applied type narrowing to ensure variables and return types are of expected types.

🎥 Artifacts

✔️ Checklist

• [ ] Changelog entry in the readme.txt file.
• [ ] Code is covered by NEW wpunit or integration tests.
• [ ] Code is covered by EXISTING wpunit or integration tests.
• [ ] Are all the required tests passing?
• [ ] Automated code review comments are addressed.
• [ ] Have you added Artifacts?
• [ ] Check the base branch for your PR.
• [ ] Add your PR to the project board for the release.