Part of #35665

Description

Knobs are now deprecated. New stories should be written using Controls, as this will make things much simpler both in terms of initial setup and adding additional stories using args composition.

Proposed changes

• Install @storybook/addon-controls.
• Disable @storybook/addon-knobs globally by default.
• Enable Knobs on a per-component basis where they are currently used.
• Update Storybook example in CONTRIBUTING.md to show how Controls can be used to write simple and composable stories.

The intent is to discourage further use of Knobs, and to make it easier to migrate to Controls whenever existing stories are reworked.

How has this been tested?

✅ A search for from '@storybook/addon-knobs' matches 50 story files. All 50 of these files have been touched to enable Knobs specifically on that file.
✅ npm run storybook:dev and check that the Controls panel is enabled, and the Knobs panel is enabled only where currently used.

Types of changes

Storybook only, no breaking changes

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).