[PP-1] Support #[AsEventListener] attribute on classes and methods

I took a look at this issue and gave an attempt to try to work with what we have, by supplementing ContainerAwareEventDispatcher with changes, and keeping our existing tag.

But I realize that we also need to add a compiler pass to reflect on tagged services.

So I agree that It might just be more straightforward to switch from \Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher to \Symfony\Component\EventDispatcher\EventDispatcher and utilize Symfony's\Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass here.

Since the associated MR came to the same conclusion, that swapping to Symfonys EventDispatcher is necessary, I think we should postpone this issue on our main EventDispatcher issue @ 📌 Replace ContainerAwareEventDispatcher with Symfony EventDispatcher Fixed

It'd be valuable to also rely on ✨ Directory based automatic service creation Needs review to do automatic service creation for us.