Allow CLI to display objectstore stats

[kaihoffman]

The Civo API allows for objectstore-specific stats to display remaining capacity and number of objects:

curl -H "Authorization: bearer <your-api-key>" <a target="_blank" data-stringify-link="https://api.civo.com/v2/objectstores/" delay="150" data-sk="tooltip_parent" href="https://api.civo.com/v2/objectstores/" rel="noopener noreferrer">https://api.civo.com/v2/objectstores/</a><your-objectstore-id>/stats?region=<region-name>
Response will be something like this
{
  "size_kb_utilised": 27449274,
  "max_size_kb": 500000000,
  "num_objects": 2408
}

This is not available on the CLI from what I can see? Would be great to either have as civo objecstore stats <NAME> or as part of the civo objectstore show <NAME> output.