Allow AjaxResponse to be altered

Thanks! RTBC+1

The patch at #8 does not work on Drupal 10.1 which has a newer version of symfony. On Symfony 4.3+ the dispatch method has been changed
from
public function dispatch($eventName, Event $event = null);
to
public function dispatch(object $event, ?string $eventName = null): object;

This new patch addresses that issue. It's a one line change.

The patch in #13 works correctly for drupal 10.1+.
I've been using it in production for a while now, with no issues. Thanks!