REST API: Add terms search handler

[TimothyBlynJacobs]

This is a tracking ticket for merging the Terms search handler from Gutenberg.

​https://github.com/WordPress/gutenberg/blob/master/lib/class-wp-rest-term-search-handler.php

[noisysocks]

Let's add ​https://github.com/WordPress/gutenberg/blob/master/lib/class-wp-rest-post-format-search-handler.php too.

[TimothyBlynJacobs]

@noisysocks see #51459.

Trac ticket: https://core.trac.wordpress.org/ticket/51458

@noisysocks Could you give this a test with Gutenberg active?

@noisysocks Could you give this a test with Gutenberg active?

It works 👍

I suspect the handler added by Core is used as it's first in the array. We should update Gutenberg to not add the handler if there is already one.

[TimothyBlynJacobs]

In 49103:

REST API: Introduce search term handler.

This allows for clients to search the available terms via the /wp/v2/search endpoint by using a type=term query parameter.

Fixes #51458.
Props andraganescu, zieladam, noisysocks, TimothyBlynJacobs.

Merged in 5b6f5f9.