feat: Add support for Ability Deprecation

[justlevine]

Trac ticket: https://core.trac.wordpress.org/ticket/64209

Adds a standard way to deprecate an ability without removing it.

Supersedes #10507 (relevant diff)

More specifically:

• Adds a meta.deprecated property (default null). Set it to an array to mark an ability as deprecated:

  'meta' => array(
      'deprecated' => array(
          'since'       => '2.0.0',                 // Required.
          'replacement' => 'my-plugin/new-ability', // Optional.
          'message'     => 'Additional guidance.',  // Optional.
      ),
  ),

• Deprecated abilities are hidden from wp_get_abilities() by default, but can be included with the included_deprecated arg, or by explicitly filtering for deprecated metadata.

• Retrieving or executing a deprecated ability will output a deprecation notice. The deprecated ability only outputs one deprecation notice per lifecycle. Deprecation notices on retrieval (only) are suppressed when include_deprecated or meta.deprecated is explicitly filtered by in wp_get_abilities()

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Opus 5.5
Used for: Updating the tests after changing from #10507

---

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Props jason_the_adams, gziolo, justlevine.

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