Update theme.json schema to allow for per-block management of settings.

[ryanwelcher]

Description

This PR is an attempt at addressing #36630. It separates out each of the setting objects ( border, color, spacing etc ) into individual definitions and then combines them on a per-block basis using allOf. This allows the schema to use any or all of them to create a schema that is both valid and also reflects what the block actually supports.

I have includes a single updated block in this PR so we can discuss if this is the correct approach. The core/button block only implements the controls for the border.radius option so I have updated its entry to reflect such.

How has this been tested?

Tested locally by pointing the $schema entry to the theme.json schema definition in this PR

Types of changes

Schema updates that should have no breaking affect on blocks.

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).

[ryanwelcher]

If this approach seems sound, it may make sense to merge this and then create a tracking ticket for the other blocks. I have spent a fair amount of time looking into the per-block support and can handle the creation of that ticket. It would also be a great place for new contributors to get some props.

[ajlende]

Sorry it took me so long to get around to reviewing this, but I like the idea! Let's get the merge conflicts resolved and do like you said with creating a tracking issue to update the rest of the blocks.

[ryanwelcher]

@ajlende I have addressed the merge conflicts but am blocked by some e2e tests. The navigation block e2e failures are unrelated to the changes here. Based on @youknowriad 's comment here I have also created a PR to skip the test with #37729

[ajlende]

Looks like the docgen for the theme.json broke because of the structure change. Care if I push a few commits to this branch to fix it? Otherwise, the change would be in https://github.com/WordPress/gutenberg/blob/trunk/bin/api-docs/gen-theme-reference.js.

[ryanwelcher]

Looks like the docgen for the theme.json broke because of the structure change. Care if I push a few commits to this branch to fix it? Otherwise, the change would be in https://github.com/WordPress/gutenberg/blob/trunk/bin/api-docs/gen-theme-reference.js.

Not at all! I just merged #37729 as well so be sure to pull latest trunk

[ajlende]

Not at all! I just merged #37729 as well so be sure to pull latest trunk

Cool, will do!

[ajlende]

Alright, I pushed a quick fix that will generate the same docs as before. As a follow-up when all the blocks are updated we can update the docgen to show the settings per-block.