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/form/Resources/config/validation.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" ?>
+
+<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
+
+  <class name="Symfony\Component\Form\Form">
+    <constraint name="Symfony\Component\Form\Extension\Validator\Constraints\Form" />
+    <constraint name="Symfony\Component\Validator\Constraints\Traverse">
+      <option name="traverse">false</option>
+    </constraint>
+  </class>
+</constraint-mapping>