RFE: improbe jmp get leases usability

[mangelajo]

Instead of the current fields:

➜  ~ jmp get leases --client majopela-community
NAME                                  SELECTOR                       DURATION  CLIENT                    EXPORTER
0199b9a7-652e-77ac-b8ce-599983efabee  name=majopela-orin-nx          4:00:00   ncao                      majopela-orin-nx
0199b9f4-e20d-7865-8936-347e3daec9ac  name=rnoriega-orin-agx         1:30:00   gitlab-runner-eco-nvidia  rnoriega-orin-agx
0199b9f4-efff-7adb-9ac5-c311cd6fd1d2  name=rnoriega-orin-agx         1:30:00   gitlab-runner-eco-nvidia
0199b9f5-061c-7cb2-8b49-0e04b3d35038  name=nvidia-jetson-nx-orin-0…  1:30:00   gitlab-runner-eco-nvidia  nvidia-jetson-nx-orin-01-khw-…
➜

by default provide:

NAME, CLIENT, ASSIGNED EXPORTER, EXPIRATION (in days/hours/min/sec)