Editor: add setting to disable layout content and wide size controls.

Adds support for an `allowCustomContentAndWideSize` setting in `WP_Theme_JSON` valid settings.

Props andrewserong.
Fixes #60133.


git-svn-id: https://develop.svn.wordpress.org/trunk@57247 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-theme-json.php

@@ -344,6 +344,7 @@ class WP_Theme_JSON {
 	 * @since 6.3.0 Added support for `typography.textColumns`, removed `layout.definitions`.
 	 * @since 6.4.0 Added support for `layout.allowEditing`, `background.backgroundImage`,
 	 *              `typography.writingMode`, `lightbox.enabled` and `lightbox.allowEditing`.
+	 * @since 6.5.0 Added support for `layout.allowCustomContentAndWideSize`.
 	 * @var array
 	 */
 	const VALID_SETTINGS = array(
@@ -380,9 +381,10 @@ class WP_Theme_JSON {
 			'minHeight' => null,
 		),
 		'layout'                        => array(
-			'contentSize'  => null,
-			'wideSize'     => null,
-			'allowEditing' => null,
+			'contentSize'                   => null,
+			'wideSize'                      => null,
+			'allowEditing'                  => null,
+			'allowCustomContentAndWideSize' => null,
 		),
 		'lightbox'                      => array(
 			'enabled'      => null,