Move Overrides out of theme and into functionality plugin

[claytoncollie]

Description of the Change

Small refactor to move functionality out of the theme and into the mu-plugin. Also, after some testing, the original code was not be instantiated in the theme at all. This change not only moves it but also gets it working properly again.

Closes #249

How to test the Change

1. Check out trunk
2. View the source on the frontend
3. Search for wp-emoji-styles-inline-css
4. Verify it does exist
5. Checkout this branch
6. Refresh the source
7. Verify that wp-emoji-styles-inline-css does NOT exist

Changelog Entry

Changed - moved emoji overrides from theme to plugin

Credits

Props @claytoncollie

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.

[tobeycodes]

Looks great to me. Aside from this I think we should review these actions and see if they are still relevant in 2025.