switcherPopup: Restore selected pseudo-class

- move styles to switcher-popup
- reverts a change in a code clean up that causes problems with screen readers

Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/7336
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3127>

js/ui/switcherPopup.js

@@ -494,9 +494,9 @@ export const SwitcherList = GObject.registerClass({
 
         if (this._items[index]) {
             if (justOutline)
-                this._items[index].add_style_pseudo_class('selected');
-            else
                 this._items[index].add_style_pseudo_class('highlighted');
+            else
+                this._items[index].add_style_pseudo_class('selected');
         }
 
         this._highlighted = index;