Themes: Add an indication of whether a theme is a child theme on network admin Themes screen.

This shows the parent theme name in a child theme's metadata section in the list table, in a similar way it is displayed in the theme details modal on the single site Themes screen.

Props dpik, Mista-Flo, seanchayes, poena, johnbillion, jeremyfelt, bradt, jacklenox, helen, Travel_girl, karmatosed, Presskopp, joyously, SergeyBiryukov.
Fixes #30240.
Built from https://develop.svn.wordpress.org/trunk@50978


git-svn-id: http://core.svn.wordpress.org/trunk@50587 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-ms-themes-list-table.php

@@ -728,6 +728,14 @@ class WP_MS_Themes_List_Table extends WP_List_Table {
 			);
 		}
 
+		if ( $theme->parent() ) {
+			$theme_meta[] = sprintf(
+				/* translators: %s: Theme name. */
+				__( 'Child theme of %s' ),
+				'<strong>' . $theme->parent()->display( 'Name' ) . '</strong>'
+			);
+		}
+
 		/**
 		 * Filters the array of row meta for each theme in the Multisite themes
 		 * list table.

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50977';
+$wp_version = '5.8-alpha-50978';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.