Theme Switcher: Provide an easier way to reset back to the current active theme.

* Add control for the active theme when doing a theme preview
* Highlight an active theme and move it to the top

props valendesigns, ocean90.
fixes #32002.

git-svn-id: https://develop.svn.wordpress.org/trunk@32265 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/customize-controls.css

@@ -1089,6 +1089,10 @@ body.cheatin p {
 	.wp-customizer .theme:not(.active):focus .theme-actions {
 		display: block;
 	}
+
+	.wp-customizer .theme-browser .theme.active .theme-name span {
+		display: inline;
+	}
 }
 
 @media screen and ( max-width: 640px ) {