Editor: Add author support to the wp_block post type

[fabiankaegy]

Adds author support to the wp_block post type, so the REST API returns each pattern's author. The block inserter and the Site Editor's Patterns screen use it to filter patterns by author.

Sets delete_with_user to false, so deleting a user keeps their patterns, as they may be used across the site. Without it, author support would make wp_delete_user() delete them permanently.

Also renames the Site Editor's "My patterns" view to "Site patterns", since it lists every user-created pattern, not only the current user's.

The author is already stored on every pattern and the post type's capabilities already check it. This only makes it visible to the editor.

Gutenberg PR: WordPress/gutenberg#84680

Trac ticket: https://core.trac.wordpress.org/ticket/66307

Use of AI Tools

Drafted with Claude Code, reviewed by me.

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[github-actions]

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[t-hamano]

Thanks for the PR! Since adding author support changes the behavior of wp_block beyond the REST API, I think we should add some tests:

• REST API: The blocks controller returns author in the response, and the author and author_exclude query parameters filter patterns by author.
• REST API: A user without edit_others_posts can't change the author of a pattern.
• Deleting a user: Deleting a user without reassigning their content also deletes their patterns, and reassigning moves them to the new user. This is the same behavior as templates and template parts, but it changes how patterns work today, so a test would document it as intended.
• QUnit fixtures: The REST schema gets new author arguments, so the API fixtures probably need to be regenerated.

[fabiankaegy]

Thanks @t-hamano! Added tests for all four:

• The blocks controller returns author, and author / author_exclude filter patterns by author.
• An author can't change a pattern's author (403), an editor can.
• Deleting a user keeps their patterns, and reassigning moves them to the new user. Without delete_with_user, author support would have deleted the patterns permanently (only posts and pages go to the trash). Patterns may be used across the site, so I've set delete_with_user to false to keep today's behavior.
• Regenerated the QUnit fixtures.