Refactor authentication system (#2602)

Make auth configuration available via UI, remove FOSUserBundle and SAML-Bundle dependency

src/Saml/SamlAuthFactory.php

@@ -0,0 +1,39 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Saml;
+
+use App\Configuration\SamlConfiguration;
+use OneLogin\Saml2\Auth;
+use OneLogin\Saml2\Utils;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * @final
+ */
+class SamlAuthFactory
+{
+    private $request;
+    private $configuration;
+
+    public function __construct(RequestStack $request, SamlConfiguration $configuration)
+    {
+        $this->request = $request;
+        $this->configuration = $configuration;
+    }
+
+    public function create(): Auth
+    {
+        if (null !== $this->request->getMasterRequest() && $this->request->getMasterRequest()->isFromTrustedProxy()) {
+            Utils::setProxyVars(true);
+        }
+
+        return new Auth($this->configuration->getConnection());
+    }
+}