Method append

bolt/exec/tests/utils/TempFilePath.h:58–63

  TempFilePath& operator=(const TempFilePath&) = delete;

  void append(std::string data) {
    std::ofstream file(path, std::ios_base::app);
    file << data;
    file.flush();
    file.close();
  }

  const int64_t fileSize() {
    struct stat st;