Image: Add rich image editing option to experiments page

[ajlende]

Description

As per discussion in #21024 (comment), this moves rich image editing to be an option which needs to be enabled by the user.

How has this been tested?

Run without the setting enabled and see that image editing tools are not shown.

Go to Gutenberg > Experiments and check "Enable Inline Rich Image Editing" and see that the image editing tools are shown.

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• 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.

[jasmussen]

Thanks Alex. I discovered a small issue with the image tools yesterday where selecting an image sets focus on the caption, and I needed to test some things where that issue wasn't present, so I merged this branch into my other branch, and it appears to correctly disable the image tools.

So for what it's worth, to me it seems worth it to keep Image tools merged, but disabled behind the experimental box. It allows us to fix the issues while still making it possible for users to discover issues in an easier way than checking out a PR.

[ellatrix]

Thanks you! Let's aim to unmark it as experimental by the next Gutenberg release.