message: Use platform based url system for in-app messages (lib)
diff: @@ -1641,7 +1641,7 @@ error Context::fetchMessage(const bool periodic) {
  title = root["title"].asString();
  text = root["text"].asString();
  button = root["button"].asString();
  - url = root["url"].asString();
  + url = root["url-" + shortOSName()].asString();
  last_message_id_ = root["id"].asString();
  }
  