lib: Implement Auth::getAuthChain()

Saves one use statement for auth chain usages.

refs #9660

library/Icinga/Authentication/Auth.php

@@ -4,12 +4,12 @@
 namespace Icinga\Authentication;
 
 use Exception;
-use Icinga\Authentication\UserGroup\UserGroupBackend;
 use Icinga\Application\Config;
+use Icinga\Application\Logger;
+use Icinga\Authentication\UserGroup\UserGroupBackend;
 use Icinga\Data\ConfigObject;
 use Icinga\Exception\IcingaException;
 use Icinga\Exception\NotReadableError;
-use Icinga\Application\Logger;
 use Icinga\User;
 use Icinga\User\Preferences;
 use Icinga\User\Preferences\PreferencesStore;
@@ -49,6 +49,16 @@ class Auth
         return self::$instance;
     }
 
+    /**
+     * Get the auth chain
+     *
+     * @return AuthChain
+     */
+    public function getAuthChain()
+    {
+        return new AuthChain();
+    }
+
     public function setAuthenticated(User $user, $persist = true)
     {
         $username = $user->getUsername();