Merge branch 'upstream-io_uring-bsg' of https://github.com/ljw8161/fio

* 'upstream-io_uring-bsg' of https://github.com/ljw8161/fio:
  engines/io_uring: Add bsg support for io_uring_cmd engine
  engines/sg: extract BE accessor helpers into shared sg.h
  engines/io_uring: Separate NVMe-specific logic