Added route generator

[gibahjoe]

Route generator was not being passed forward from the Route classes (ChildRoute etc) despite being implemented in ModularPage

else if (router.transition == TransitionType.defaultTransition) {
      // Helper function
      Widget widgetBuilder(BuildContext context) {
        //return disposablePage;
        return router.child!(context, router.args);
      }

      if (router.routeGenerator != null) {
        return router.routeGenerator!(widgetBuilder, this) as Route<T>;
      }
      return MaterialPageRoute<T>(
        settings: this,
        builder: widgetBuilder,
      );
    }