Add new REST API endpoint for Ability Categories

[gziolo]

Trac ticket: https://core.trac.wordpress.org/ticket/64098

Follow-up for WordPress#9410.

There is also a new REST API endpoint for Ability Categories that I put into this separate PR for transparency.

I transferred it from the Abilities API repository, updating the code based on the feedback in WordPress#9410. Example paths:

GET /wp/v2/ability-categories - all ability categories
GET /wp/v2/ability-categories/test-data-retrieval - a single ability category

The name of the controller: WP_REST_Ability_Categories_Controller.

It's very similar in every aspect to the endpoint for listing abilities.

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[Copilot]

Pull Request Overview

This PR adds a new REST API endpoint for Ability Categories as part of the WordPress Abilities API. It introduces a controller that provides read-only access to ability categories via the /wp/v2/ability-categories endpoint, supporting both collection listing and individual category retrieval.

Key changes include:

• New REST controller for ability categories with pagination support
• Registration of the controller in the WordPress REST API system
• Comprehensive test coverage for the new endpoint

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/phpunit/tests/rest-api/wpRestAbilityCategoriesController.php	Complete test suite covering all REST API endpoints, permissions, pagination, and error handling
src/wp-settings.php	Includes the new controller class file in WordPress core
src/wp-includes/rest-api/endpoints/class-wp-rest-ability-categories-controller.php	Main controller implementation with collection and item endpoints
src/wp-includes/rest-api.php	Registers the controller routes during REST API initialization
src/wp-includes/abilities-api/class-wp-ability.php	Updates @subpackage documentation formatting
src/wp-includes/abilities-api/class-wp-ability-category.php	Updates @subpackage documentation formatting
src/wp-includes/abilities-api/class-wp-ability-categories-registry.php	Updates @subpackage documentation formatting
src/wp-includes/abilities-api/class-wp-abilities-registry.php	Updates @subpackage documentation formatting

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[gziolo]

I opened WordPress#10354 with all changes tested against WordPress trunk, and CI checks pass after adding a few tweaks to unit tests setup with 895bb88.

[gziolo]

Superseeded by WordPress#10380 and commited with 871fd0e.