window-list: Set title and icon on prefs page

Like the workspace prefs page, the existing window list prefs
should set title and icon for the view switcher.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/344>

extensions/window-list/prefs.js

@@ -18,7 +18,10 @@ class WindowListPrefsWidget extends Adw.PreferencesPage {
     }
 
     constructor(settings) {
-        super();
+        super({
+            title: _('Window List'),
+            icon_name: 'focus-windows-symbolic',
+        });
 
         this._actionGroup = new Gio.SimpleActionGroup();
         this.insert_action_group('window-list', this._actionGroup);