add nvme-cli functionality for `nvme_lm_get_feature` command

[kurz-m]

While refactoring for the new libnvme API, we discovered that there is no functionality for nvme_lm_get_feature within the nvme-cli tool.

This Issue should remind us to implement it at some point.

[ikegami-t]

Looks already the nvme lm get-cdq command itself supported for this issue.

tokunori@tokunori-X570-Taichi:~/nvme-cli$ nvme lm 
nvme-2.13
usage: nvme lm <command> [<device>] [<args>]

The '<device>' may be either an NVMe character device (ex: /dev/nvme0), an
nvme block device (ex: /dev/nvme0n1), or a mctp address in the form
mctp:<net>,<eid>[:ctrl-id]

Live Migration NVMe extensions

The following are all implemented sub-commands:
  create-cdq       Create Controller Data Queue
  delete-cdq       Delete Controller Data Queue
  track-send       Track Send Command
  migration-send   Migration Send
  migration-recv   Migration Receive
  set-cdq          Set Feature - Controller Data Queue (FID 21h)
  get-cdq          Get Feature - Controller Data Queue (FID 21h)
  version          Shows the program version
  help             Display this help

See 'nvme lm help <command>' for more information on a specific command
tokunori@tokunori-X570-Taichi:~/nvme-cli$ nvme lm get-cdq -h
Usage: nvme lm get-cdq <device> [OPTIONS]

This Feature allows a host to retrieve the status of the head pointer of a
CDQ and specify the configuration of a CDQ Tail event.

Options:
  [  --cdqid=<NUM>, -C <NUM> ]          --- Controller Data Queue ID
  [  --output-format=<FMT>, -o <FMT> ]  --- Output format: normal|json|binary