sks nodepool: show instance family

[sauterp]

Checklist

(For exoscale contributors)

• Changelog updated (under Unreleased block)
• Testing

Testing

❯ ./bin/exo -A exosauterp compute sks nodepool show abc def -z ch-gva-2
┼─────────────────────────┼──────────────────────────────────────┼
│      SKS NODEPOOL       │                                      │
┼─────────────────────────┼──────────────────────────────────────┼
│ Instance Type           │ standard.medium                      │
┼─────────────────────────┼──────────────────────────────────────┼

[horakg]

Will it be shown like this:
Instance Type │ cpu.extra-large

or will we get two lines like above, currently we always show "." in all other outputs

[sauterp]

Will it be shown like this: Instance Type │ cpu.extra-large

or will we get two lines like above, currently we always show "." in all other outputs

I changed it to be consistent with other show commands. The output is as shown in the PR description.