Description

Partly addresses #31965. Related to #31965 and #34135.

Migrates post editor feature preferences over to the interface package.

Here there was a choice of deprecating the post editor's APIs for features, but this keeps them as backwards compatibility is pretty easy to maintain. Any selectors and actions call through to the interface store's implementation.

How has this been tested?

1. Checkout trunk and open the post editor.
2. Set some preferences to a value different to the default (e.g. 'Top toolbar' and 'Contain cursor inside block' to active.)
3. Checkout this branch, rebuild and open up the post editor
4. The welcome guide should not show and the preferences should be retained from step 2.
5. Clear browser storage (or just the WP_DATA_USER_ values) and reload
6. Open up the customize widgets editor, the welcome guide should be shown
7. Try toggling various settings to ensure they work.

Types of changes

New feature (non-breaking change which adds functionality)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).