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/RemovePrivateAliasesPass.php

@@ -24,6 +24,8 @@ class RemovePrivateAliasesPass implements CompilerPassInterface
 {
     /**
      * Removes private aliases from the ContainerBuilder.
+     *
+     * @return void
      */
     public function process(ContainerBuilder $container)
     {