Add UserGroup to chill (import from branch ticket-app-master)

Import the UserGrou feature from ticket-app-master branch. This includes:

- import all the entities and migrations, modification of typescript types, templating, and so on;
- apply some verification and formatting rules, like:
  - reformat file on chill.api.specs.yaml (MainBundle)
  - reformat file on types.ts (Main Bundle)

Migrations kept the same filename.

src/Bundle/ChillMainBundle/Controller/UserGroupApiController.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\MainBundle\Controller;
+
+use Chill\MainBundle\CRUD\Controller\ApiController;
+
+class UserGroupApiController extends ApiController {}