Added part of backend but problems with Joomla code compatibility found.

Somehow the password must be handled specially (also because of the hashing) which causes problems at the moment.

src/admin/controllers/user.php

@@ -0,0 +1,11 @@
+<?php
+
+use Joomla\CMS\MVC\Controller\FormController;
+
+// No direct access.
+defined('_JEXEC') or die;
+
+class ClubsControllerUser extends FormController
+{
+    
+}