Add $schema property to block and theme JSON files

[jonsurrell]

Add $schema to block.json and theme.json files to leverage JSON schema support.

Schemas help ensure that these files conform to expectations. They can help provide autocomplete and documentation if editors are configured to do so.

We provide and maintain these schemas, we should be using them. This can help to ensure that our own declarations are correct and that the schemas are also correct.

See ​https://github.com/WordPress/gutenberg/pull/57201

Add $schema to block.json and theme.json files.

This is a port of ​https://github.com/WordPress/gutenberg/pull/57201

Trac ticket: https://core.trac.wordpress.org/ticket/60255

Add $schema to block.json and theme.json files to leverage JSON schema support.

Schemas help ensure that these files conform to expectations. They can help provide autocomplete and documentation if editors are configured to do so.

We provide and maintain these schemas, we should be using them. This can help to ensure that our own declarations are correct and that the schemas are also correct.

​https://github.com/WordPress/wordpress-develop/actions/runs/7529540433/job/20493970875?pr=5868

Files in src/wp-includes/blocks are synced from npm packages so they will get updated next time WordPress packages get updated.

Good to know, thanks! I reverted the changes to src/wp-includes/blocks.

@sirreal it looks like some of these should come over through the normal package update process? do you know if this is true?

src/wp-includes/blocks changes should be updated automatically (​https://github.com/WordPress/wordpress-develop/pull/5868#issuecomment-1892189866) - I had changed those files but reverted the changes.

I've taken the liberty of slightly tweaking the test hooked blocks' names in ​https://github.com/WordPress/wordpress-develop/pull/5868/commits/126b31bf0dc64ae3f8a017bb015346f92ea9a739. Hope that's okay! 😊

Looks good, thanks @ockham.

[Bernhard Reiter]

In 57336:

General: Add $schema property to block and theme JSON files.

Additionally, this changeset fixes some of the block.json and theme.json files in PHPUnit tests by adding missing title properties to satisfy the schema. Those changes have no impact on the runtime whatsoever and do not change the result of unit tests.

Note that some block and theme JSON files still aren't valid according to the schema. Fixing is underway; the required changes will be merged subsequently.

Props jonsurrell, dmsnell, gziolo.
Fixes #60255.

Committed to Core in https://core.trac.wordpress.org/changeset/57336.