Method ThreadPoolExecutor

src/babylon/executor.h:258–258

Use **this** in worker thread, so no copy nor move

 public:
  // Use **this** in worker thread, so no copy nor move
  ThreadPoolExecutor() = default;
  ThreadPoolExecutor(ThreadPoolExecutor&&) noexcept = delete;
  ThreadPoolExecutor(const ThreadPoolExecutor&) noexcept = delete;
  ThreadPoolExecutor& operator=(ThreadPoolExecutor&&) noexcept = delete;