Add functionality to import known DID to "phonebook"

[nickreynolds]

No description provided.

[simonas-notcat]

@nickreynolds how do you think this should work?

If the "phonebook" is just a collection of credentials, would this import/create VCs about a DID?

[nickreynolds]

I think that in the first iteration, the phonebook isn't a collection of credentials, but just a collection of identifiers. So the user would be able to import a DID to be stored in the identifier table, as a non-agent-managed-DID. Later we could query related Profile Credentials for each DID to provide additional context