Submits an NVMe Directive Send admin command and returns the applicable
results. This may be the combination of directive type, and operation, as
well as target directive and its enable/disable status of the operation,
if specific operation needs it.
The <device> parameter is mandatory and may be either the NVMe character
device (ex: /dev/nvme0), or a namespace block device (ex: /dev/nvme0n1).
On success, the returned directive’s parameter structure (if applicable) is
returned in one of several ways depending on the option flags; the
structure may parsed by the program and printed in a readable format
if it is a known structure, displayed in hex, or the raw buffer may be
printed to stdout for another program to parse.