Nicer config syntax for PSR-4 route loading

Author: derrabus

Tests/Functional/app/Psr4Routing/routing.yml

@@ -1,4 +1,6 @@
 test_bundle:
     prefix:   /annotated
-    resource: "@TestBundle/Controller"
-    type:     attribute@Symfony\Bundle\FrameworkBundle\Tests\Functional\Bundle\TestBundle\Controller
+    resource:
+        path: "@TestBundle/Controller"
+        namespace: Symfony\Bundle\FrameworkBundle\Tests\Functional\Bundle\TestBundle\Controller
+    type:     attribute