refactor: loader only approach

[kellymears]

This is a broad refactor.

I wanted to suggest this approach as I think it simplifies things a great deal and makes the functionality fully cacheable in a straight forward way.

Two major notes:

1. I did not implement adoption because I did not fully understand the distinction between include and adopt.
   But, whatever it is, I think it could be added back with some conditional checks in the WpEditorRemoveRules plugin.

2. I don't think my handling of AtRules edge cases is as thorough as yours. To be honest, I didn't want to have to deal with all the intricacies, I only wanted to prove the concept. The robustness of the existing approach could/should be added back in.

Feel free to re-implement it, add to it, ignore it. Thanks!

[talss89]

Thanks a lot for this. Your take on it made me rethink things.

I've rewritten the plugin as a bud extension in ESM / TS, using your loader only approach.

Still had to put in a bit of jank to make it work properly with all the combinations of @media syntax.

Closing this PR in favour of the new extension: https://github.com/talss89/bud-wp-editor-query