`identities unclaim` command

[amydevs]

Specification

We already have an identities claim command.

Therefore, there should be a way to unclaim once you have already created a claim on certain identity provider.

In polykey, we have a publishClaim method on the abstract Provider class. Similarly, there should be an unpublishClaim method.

This will make it so that the user does not have to manually figure out what website and what claim corresponds to the NodeID that they would like to unclaim.

Additional context

#163

Tasks

1. Implement unpublishClaim abstract method on Provider class in polykey.
2. Create identitiesUnclaim RPC handler in polykey.
3. Create identities unclaim command in Polykey-CLI

[linear]

ENG-32 `identities unclaim` command