feat: allow starting session from extenders

src/Webservice/WebService.php

@@ -69,6 +69,12 @@ abstract class WebService
         $renderer->render($this->status, $data);
     }
 
+    protected function startSession()
+    {
+        session_save_path(Configuration::get('session.save_path'));
+        session_start();
+    }
+
     /**
      * Determines which method to call based on GET or POST parameters and
      * call it before returning the result.
@@ -80,8 +86,7 @@ abstract class WebService
     private function call($sendSession = true)
     {
         if ($sendSession) {
-            session_save_path(Configuration::get('session.save_path'));
+            $this->startSession();
-            session_start();
         }
 
         $params = empty($_GET) ? $_POST : $_GET;