bug #62184 [EventDispatcher][FrameworkBundle] Rework union types on #[AsEventListener] (HypeMC)

This PR was merged into the 7.4 branch.

Discussion
----------

[EventDispatcher][FrameworkBundle] Rework union types on `#[AsEventListener]`

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

This is a reimplementation of #61252.
The previous PR introduced a backward compatibility break.

Consider the following listener:

```php
final class TestListener
{
    #[AsEventListener(event: RequestEvent::class)]
    public function onRequestEvent(): void
    {
        // ...
    }
}
```

In earlier versions, this worked fine, but now it throws:

> AsEventListener attribute requires the first argument of "App\EventListener\TestListener::onRequestEvent()" to be an event object.

Interestingly, there *was* a test for this scenario, but since each test method re-defines the `registerAttributeForAutoconfiguration()` closure (which wasn't updated everywhere), the tests still passed.

Additionally, the implementation was added to the `FrameworkExtension`, even though similar logic already existed in `RegisterListenersPass::getEventFromTypeDeclaration()`, resulting in a decentralized implementation.

This PR reverts the changes in `FrameworkExtension` and re-implements the feature in `RegisterListenersPass`.
The tests now reuse the closure from `FrameworkExtension` to make them more robust and consistent with the actual implementation.

Commits
-------

8ea7196e9c9 [EventDispatcher][FrameworkBundle] Rework union types on `#[AsEventListener]`

Author: nicolas-grekas

DependencyInjection/FrameworkExtension.php

@@ -779,32 +779,13 @@ public function load(array $configs, ContainerBuilder $container): void
 
         $container->registerAttributeForAutoconfiguration(AsEventListener::class, static function (ChildDefinition $definition, AsEventListener $attribute, \ReflectionClass|\ReflectionMethod $reflector) {
             $tagAttributes = get_object_vars($attribute);
-
-            if (!$reflector instanceof \ReflectionMethod) {
-                $definition->addTag('kernel.event_listener', $tagAttributes);
-
-                return;
-            }
-
-            if (isset($tagAttributes['method'])) {
-                throw new LogicException(\sprintf('AsEventListener attribute cannot declare a method on "%s::%s()".', $reflector->class, $reflector->name));
-            }
-
-            $tagAttributes['method'] = $reflector->getName();
-
-            if (!$eventArg = $reflector->getParameters()[0] ?? null) {
-                throw new LogicException(\sprintf('AsEventListener attribute requires the first argument of "%s::%s()" to be an event object.', $reflector->class, $reflector->name));
-            }
-
-            $types = ($type = $eventArg->getType() instanceof \ReflectionUnionType ? $eventArg->getType()->getTypes() : [$eventArg->getType()]) ?: [];
-
-            foreach ($types as $type) {
-                if ($type instanceof \ReflectionNamedType && !$type->isBuiltin()) {
-                    $tagAttributes['event'] = $type->getName();
-
-                    $definition->addTag('kernel.event_listener', $tagAttributes);
+            if ($reflector instanceof \ReflectionMethod) {
+                if (isset($tagAttributes['method'])) {
+                    throw new LogicException(\sprintf('AsEventListener attribute cannot declare a method on "%s::%s()".', $reflector->class, $reflector->name));
                 }
+                $tagAttributes['method'] = $reflector->getName();
             }
+            $definition->addTag('kernel.event_listener', $tagAttributes);
         });
         $container->registerAttributeForAutoconfiguration(AsController::class, static function (ChildDefinition $definition, AsController $attribute): void {
             $definition->addTag('controller.service_arguments');