Refactor authentication system (#2602)

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

phpunit.xml.dist

@@ -25,6 +25,7 @@
         <env name="DATABASE_URL" value="mysql://kimai2_test:kimai2_test@127.0.0.1:3306/kimai2_test"/>
         <env name="CORS_ALLOW_ORIGIN" value="^https?://localhost(:[0-9]+)?$"/>
         <env name="MAILER_URL" value="null://null"/>
+        <env name="MAILER_FROM" value="kimai@example.com"/>
 
         <!--
             REINSTALL THE TEST DATABASE, AFTER CHANGING STRUCTURE?