REST API: Support the (min|max)Items JSON Schema keywords.

A future commit will add support for the uniqueItems keyword.

Props sorenbronsted.
See #48821.


git-svn-id: https://develop.svn.wordpress.org/trunk@47923 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/rest-api/rest-test-controller.php

@@ -101,11 +101,13 @@ class WP_REST_Test_Controller extends WP_REST_Controller {
 					'default' => 'a',
 				),
 				'somearray'      => array(
-					'type'    => 'array',
-					'items'   => array(
+					'type'     => 'array',
+					'items'    => array(
 						'type' => 'string',
 					),
-					'context' => array( 'view' ),
+					'minItems' => 1,
+					'maxItems' => 10,
+					'context'  => array( 'view' ),
 				),
 				'someobject'     => array(
 					'type'                 => 'object',