Abilities API: Add the initial core abilities and categories registration.

[jorgefilipecosta]

Trac ticket: https://core.trac.wordpress.org/ticket/64146

Backports the initial WordPress core abilities proposed at WordPress/abilities-api#108 with improvements in preparation for core at WordPress/abilities-api#128, into Core WordPress.

Testing

Verify the unit tests are passing.
Loaded the block editor, oppened the browser console, exectuted the following two calls:

wp.apiFetch({ path: wp.url.addQueryArgs('/wp-abilities/v1/abilities/core/get-site-info/run' ) } ).then(console.log);
wp.apiFetch({ path: wp.url.addQueryArgs('/wp-abilities/v1/abilities/core/get-site-info/run', {input: {fields: ['name','url' ] } } ) } ).then(console.log);

Verified things returned as expected.

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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Core Committers: Use this line as a base for the props when committing in SVN:

Props jorgefilipecosta, gziolo, mukesh27.

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[github-actions]

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Test this pull request with WordPress Playground.

[gziolo]

Nice one, thank you for working on syncing this code from Abilities API repository. I see you applied the feedback from @aaronjorbin regarding how the code is structured 👍🏻

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61063
GitHub commit: 9824c6f

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.