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/dependency-injection/Compiler/CompilerPassInterface.php

@@ -22,6 +22,8 @@ interface CompilerPassInterface
 {
     /**
      * You can modify the container here before it is dumped to PHP code.
+     *
+     * @return void
      */
     public function process(ContainerBuilder $container);
 }