Add reset button to Layout controls

[Mamaduka]

Adds reset button to the Layout controls, similar to other custom value controls.

Fixes #30614.

Screenshots

Types of changes

New feature

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).

[carolinan]

LGTM.