Global styles: preload /global-styles endpoint responses

This commit fixes a regression whereby requests to global styles endpoints were not being preloaded, resulting in several requests being fired clientside unnecessarily.  

For performance reasons, we  preload the requests so that the data is in the editor store and ready to use straight away.  

The outcome is that the editor loads more quickly.

Follow-up to [62042].

Props ellatrix, ramonopoly, apermo, peterwilsoncc.
Fixes #62315.



git-svn-id: https://develop.svn.wordpress.org/trunk@59316 602fd350-edb4-49c9-b593-d223f7449a82

Author: ramonjd

src/wp-admin/edit-form-blocks.php

@@ -51,6 +51,8 @@ static function ( $classes ) {
 
 $rest_path = rest_get_route_for_post( $post );
 
+$active_theme = get_stylesheet();
+
 // Preload common data.
 $preload_paths = array(
 	'/wp/v2/types?context=view',
@@ -65,8 +67,10 @@ static function ( $classes ) {
 	sprintf( '%s/autosaves?context=edit', $rest_path ),
 	'/wp/v2/settings',
 	array( '/wp/v2/settings', 'OPTIONS' ),
-	'/wp/v2/global-styles/themes/' . get_stylesheet(),
+	'/wp/v2/global-styles/themes/' . $active_theme . '?context=view',
+	'/wp/v2/global-styles/themes/' . $active_theme . '/variations?context=view',
 	'/wp/v2/themes?context=edit&status=active',
+	array( '/wp/v2/global-styles/' . WP_Theme_JSON_Resolver::get_user_global_styles_post_id(), 'OPTIONS' ),
 	'/wp/v2/global-styles/' . WP_Theme_JSON_Resolver::get_user_global_styles_post_id() . '?context=edit',
 );
 

src/wp-admin/site-editor.php

@@ -97,8 +97,9 @@ static function ( $classes ) {
 	'/wp/v2/template-parts?context=edit&per_page=-1',
 	'/wp/v2/themes?context=edit&status=active',
 	'/wp/v2/global-styles/' . $active_global_styles_id . '?context=edit',
-	'/wp/v2/global-styles/' . $active_global_styles_id,
-	'/wp/v2/global-styles/themes/' . $active_theme,
+	array( '/wp/v2/global-styles/' . $active_global_styles_id, 'OPTIONS' ),
+	'/wp/v2/global-styles/themes/' . $active_theme . '?context=view',
+	'/wp/v2/global-styles/themes/' . $active_theme . '/variations?context=view',
 	array( $navigation_rest_route, 'OPTIONS' ),
 	array(
 		add_query_arg(