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/LazyProxy/ProxyHelper.php

@@ -11,10 +11,12 @@
 
 namespace Symfony\Component\DependencyInjection\LazyProxy;
 
+trigger_deprecation('symfony/dependency-injection', '6.2', 'The "%s" class is deprecated, use "%s" instead.', ProxyHelper::class, \Symfony\Component\VarExporter\ProxyHelper::class);
+
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  *
- * @internal
+ * @deprecated since Symfony 6.2, use VarExporter's ProxyHelper instead
  */
 class ProxyHelper
 {