MAPG-184 measure runtime and show in web output

src/Response/JsonContent.php

@@ -9,6 +9,8 @@ class JsonContent extends ContentBase
 
     public function &render(): string
     {
+        $this->data['__debug__runtime'] = round((hrtime(true) - SCRIPT_STARTED) / 1e+6, 1);
+
         $content = json_encode($this->data);
 
         return $content;