Add get and post/pages abilities

[jorgefilipecosta]

This tracks the addition of get abilities for post types via the Abilities API, enabling AI agents to retrieve posts and pages through core/post-type/{slug}/get. It should introduce a show_in_abilities option on register_post_type() to control which post types expose abilities, enabled by default for post and page initially (then we can expand to menus, media etc)-
It should support single-post retrieval by ID and multi-post querying with filters for status, author, search, taxonomy, meta, date, comment status, ping status, advanced taxonomies, date or meta queries.

Added get abilities for post types via the Abilities API, enabling AI agents to retrieve posts and pages through core/post-type/{slug}/get.

Trac ticket: https://core.trac.wordpress.org/ticket/64606

## Use of AI Tools

[desrosj]

Moving tickets related to the Abilities API to a new sub-component.

[audrasjb]

Removing trunk version as this is not going to be shipped with WP 7.0 but in the next releases.

[desrosj]

Removing abilities and abilities-api custom keywords. This is now indicated by the Abilities API component.

[desrosj]

Since this is an enhancement, there's no first version of WordPress this can be reproduced in. Removing trunk version.