Support listing all claims and retrieving claim detail

[plombardi89]

Once we have multiple claims in the backend and CLI there needs to be a way to actually see all the active claims that a user has.

There should also be a way to get detailed information about a claim such as duration, kubernetes version, and the URL. It would be nice if this information could also be formatted in either text or JSON format for easy consumption from tooling.

[plombardi89]

@kflynn also would like a mechanism to just check if a claim exists. I might add this via kubernaut get-claim <id> --check or something (CLI naming still TBD)