REST API: Extract get_endpoint_args_for_item_schema to standalone function

[TimothyBlynJacobs]

The WP_REST_Controller:get_endpoint_args_for_item_schema() method allows converting a schema to an args format for WP_REST_Request. This is a helpful function for whenever you want to apply this kind of conversion, but since it is a part of the WP_REST_Controller class, and doesn't accept the schema to transform directly, doing this conversion is tricky.

I think it'd be helpful to extract this to a standalone rest_get_endpoint_args_for_schema( $schema, $method ) function that the existing method in WP_REST_Controller can then call.

• Extract get_endpoint_args_for_item_schema to standalone rest_get_endpoint_args_for_schema function
• Update unit test rest-controller.php, change focus to rest_get_endpoint_args_for_schema

https://core.trac.wordpress.org/ticket/50876

[pentatonicfunk]

Couldn't agree more, exposing this function will give more benefits to developers.
I've create initial PR.

[TimothyBlynJacobs]

In 48951:

REST API: Extract WP_REST_Controller::get_endpoint_args_for_item_schema() to a standalone function.

This method is useful whenever a JSON Schema needs to be converted to a format suitable for argument validation with WP_REST_Request. Moving the logic into a standalone function allows developers to use it outside of the WP_REST_Controller context.

Props pentatonicfunk.
Fixes #50876.

[TimothyBlynJacobs]

This is great, thanks for working on the patch @pentatonicfunk!

Merged in 84d524e. Thanks again for the patch!