Editor: Add new theme category for block types

Related: https://github.com/WordPress/gutenberg/pull/30020.

Introduces a new "theme" category to the default set to use with template-parts and other FSE blocks.

Props matveb.
Fixes #52883. 


Built from https://develop.svn.wordpress.org/trunk@50564


git-svn-id: http://core.svn.wordpress.org/trunk@50177 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/post.php

@@ -2206,6 +2206,11 @@ function get_block_categories( $post ) {
 			'title' => _x( 'Widgets', 'block category' ),
 			'icon'  => null,
 		),
+		array(
+			'slug'  => 'theme',
+			'title' => _x( 'Theme', 'block category' ),
+			'icon'  => null,
+		),
 		array(
 			'slug'  => 'embed',
 			'title' => _x( 'Embeds', 'block category' ),

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50563';
+$wp_version = '5.8-alpha-50564';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.