Method dequeue

src/common/utils/BoundedQueue.h:35–41

  }

  T dequeue() {
    dequeueSemaphore_.wait();
    T item;
    queue_.readIfNotEmpty(item);
    enqueueSemaphore_.signal();
    return item;
  }

  folly::coro::Task<T> co_dequeue() {
    co_await dequeueSemaphore_.co_wait();