message: Add error string to QUIC EchoClient's connection error message
  Summary: for
diff: @@ -82,7 +82,8 @@ class EchoClient : public quic::QuicSocket::ConnectionCallback,
  void onConnectionError(
  std::pair<quic::QuicErrorCode, std::string> error) noexcept override {
  - LOG(ERROR) << "EchoClient error: " << toString(error.first);
  + LOG(ERROR) << "EchoClient error: " << toString(error.first)
  + << "; errStr=" << error.second;
  startDone_.post();
  }
  