ublk_drv: support UBLK_F_USER_RECOVERY_REISSUE

ublk_drv: support UBLK_F_USER_RECOVERY_REISSUE

UBLK_F_USER_RECOVERY_REISSUE implies that:
With a dying ubq_daemon, ublk_drv let monitor_work requeues rq issued to
userspace(ublksrv) before the ubq_daemon is dying.

UBLK_F_USER_RECOVERY_REISSUE is designed for backends which:
(1) tolerate double-write since ublk_drv may issue the same rq
    twice.
(2) does not let frontend users get I/O error, such as read-only FS
    and VM backend.

Signed-off-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220923153919.44078-6-ZiyangZhang@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>