nbft: add the nbft show plugin

nbft: add the nbft show plugin

Display contents of the ACPI NBFT files.

Usage: nvme nbft show <device> [OPTIONS]

Options:
  [  --output-format=<FMT>, -o <FMT> ]  --- Output format: normal|json
  [  --subsystem, -s ]                  --- show NBFT subsystems
  [  --hfi, -H ]                        --- show NBFT HFIs
  [  --discovery, -d ]                  --- show NBFT discovery controllers
  [  --nbft-path=<STR> ]                --- user-defined path for NBFT tables

Signed-off-by: Stuart Hayes <stuart_hayes@dell.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: John Meneghini <jmeneghi@redhat.com>