message: add connect udp flag
  Summary:
  Add the connect udp flag as an option to hq. Also set the default tperf client behavior
  to use a connected udp socket.
diff: @@ -342,6 +342,7 @@ class TPerfClient : public quic::QuicSocket::ConnectionCallback,
  auto settings = quicClient_->getTransportSettings();
  settings.advertisedInitialUniStreamWindowSize = window_;
  settings.advertisedInitialConnectionWindowSize = 10 * window_;
  + settings.connectUDP = true;
  quicClient_->setTransportSettings(settings);
  LOG(INFO) << "TPerfClient connecting to " << addr.describe();
  