BUGFIX: Correctly define manage assets privilege

The previously defined privilege on the controller had no effect as the controller
didn’t have any relevant actions to modify assets.

Therefore the privilege was adjusted to target the mutationresolver which contains
all methods to modify assets.

Configuration/Policy.yaml

@@ -1,7 +1,7 @@
 privilegeTargets:
   'Neos\Flow\Security\Authorization\Privilege\Method\MethodPrivilege':
     'Flowpack.Media.Ui:ManageAssets':
-      matcher: 'method(public Flowpack\Media\Ui\Controller\MediaController->(.*)Action())'
+      matcher: 'method(Flowpack\Media\Ui\GraphQL\Resolver\Type\MutationResolver->.*())'
     'Flowpack.Media.Ui:Queries':
       matcher: 'method(public Flowpack\Media\Ui\GraphQL\Resolver\(.*)Resolver->.*()) || method(t3n\GraphQL\Controller\GraphQLController->queryAction())'