REST API: Post types and taxonomies labels

[aduth]

Related: #2489 (comment)

Relevant APIs:

• https://developer.wordpress.org/reference/functions/register_post_type/
• https://developer.wordpress.org/reference/functions/register_taxonomy/
• https://developer.wordpress.org/reference/functions/get_post_type_labels/
• https://developer.wordpress.org/reference/functions/get_taxonomy_labels/

Prior art:

• https://developer.wordpress.com/docs/api/1.1/get/sites/%24site/post-types/%24post_type/taxonomies/

There's a need to show post type and taxonomy labels in the Gutenberg interface. This will enhance the experience of related workflows such as "Add New Genre" (for a genre custom taxonomy) in place of the generic "Add New Tag".

Potentially, this ties into a larger need for sharing localized strings between the server and client, but in these cases the strings are very dynamic (depending on which post types / taxonomies registered).

Potential solutions may include bootstrapping localized strings from the server using wp_localize_script, but it opens concerns of:

• How scalable is this approach for increasingly client-based interfaces? Media library strings are the closest example and are already quite unwieldy.
• What solution is there for interfaces consuming from the REST API which don't have the option to bootstrap from the server (e.g. static single-page applications)?

[TimothyBJacobs]

Both the wp/v2/types and wp/v2/taxonomies endpoints should contain the labels.

[aduth]

On pointers from @rmccue and confirming in testing, I did find both the types and taxonomies endpoints include labels when specifying ?context=edit