Read attributes as provided by the event object, and pass on attributes to other event handlers (Case 177753)

[MalteWunsch]

This adapts webfactory/WebfactoryWfdMetaBundle#53:

This PR uses the new API introduced in symfony/symfony#46001 to read controller attributes through the ControllerEvent, and to make them available to other event handlers when replacing the controller.

This is necessary when using the Send304IfNotModified attribute in combination with \Symfony\Component\HttpKernel\Attribute\Cache. Without this change, \Symfony\Component\HttpKernel\EventListener\CacheAttributeListener will not set Cache headers accordingly. The result is that you may get 304 Not Modified responses on conditional requests with If-Modified-Since, but these are treated as stale/cache only in the HttpCache and have a Cache-Control: must-revalidate, private header.

And adds some tests.