Function type_id

cpp/src/arrow/flight/types.h:1293–1293

                                 std::vector<std::pair<std::string, std::string>> details)
      : code_(code), message_(std::move(message)), details_(std::move(details)) {}
  const char* type_id() const override { return kTypeId; }
  std::string ToString() const override;

  static std::optional<std::reference_wrapper<const TransportStatusDetail>> Unwrap(