appDisplay: Use navigate_focus() to keep focus after editing app folder title

The AppFolderDialog would lose keyboard focus after editing the title
(likely due to the folder entry grabbing key focus). This commit adds
navigate_focus() to _showFolderLabel() to send key focus back to the
dialog's elements after editing the title.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3338>

js/ui/appDisplay.js

@@ -2661,6 +2661,7 @@ export const AppFolderDialog = GObject.registerClass({
 
         this._maybeUpdateFolderName();
         this._switchActor(this._entry, this._folderNameLabel);
+        this.navigate_focus(this, St.DirectionType.TAB_FORWARD, false);
     }
 
     _showFolderEntry() {