N°6934 - Symfony 6.4 - upgrade Symfony bundles to 6.4 (#580)

* Update Symfony lib to version ~6.4.0
* Update code missing return type
* Add an iTop general configuration entry to store application secret (Symfony mandatory parameter)
* Use dependency injection in ExceptionListener & UserProvider classes

lib/symfony/http-kernel/Controller/ControllerResolverInterface.php

@@ -37,5 +37,5 @@ interface ControllerResolverInterface
      *
      * @throws \LogicException If a controller was found based on the request but it is not callable
      */
-    public function getController(Request $request);
+    public function getController(Request $request): callable|false;
 }