N°8771 - Add Symfony form component to iTop core (#760)

- Add Symfony Form Component
- Add Symfony CSRF security component
- Add iTop default form template
- Add Twig debug extension to Twig Environment
- Add iTop abstract controller facility to get form builder
- Add Twig filter to make trans an alias of dict_s filter

lib/symfony/security-core/Exception/SessionUnavailableException.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Security\Core\Exception;
+
+/**
+ * This exception is thrown when no session is available.
+ *
+ * Possible reasons for this are:
+ *
+ *     a) The session timed out because the user waited too long.
+ *     b) The user has disabled cookies, and a new session is started on each
+ *        request.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ * @author Alexander <iam.asm89@gmail.com>
+ */
+class SessionUnavailableException extends AuthenticationException
+{
+    public function getMessageKey(): string
+    {
+        return 'No session available, it either timed out or cookies are not enabled.';
+    }
+}