REST API: Add support for arrays in schema validation and sanitization.

By allowing more fine-grained validation and sanitisation of endpoint args, we can ensure the correct data is being passed to endpoints.

This can easily be extended to support new data types, such as CSV fields or objects.

Props joehoyle, rachelbaker, pento.
Fixes #38531.


Built from https://develop.svn.wordpress.org/trunk@39046


git-svn-id: http://core.svn.wordpress.org/trunk@38988 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/endpoints/class-wp-rest-controller.php

@@ -559,7 +559,7 @@ abstract class WP_REST_Controller {
 				$endpoint_args[ $field_id ]['required'] = true;
 			}
 
-			foreach ( array( 'type', 'format', 'enum' ) as $schema_prop ) {
+			foreach ( array( 'type', 'format', 'enum', 'items' ) as $schema_prop ) {
 				if ( isset( $params[ $schema_prop ] ) ) {
 					$endpoint_args[ $field_id ][ $schema_prop ] = $params[ $schema_prop ];
 				}