Support OpenID token refresh in clients

[dimas-b]

Currently Nessie Clients allow configuring a fixed bearer token.

If the token expires and has to be refreshed from the authentication provider, the user will have to re-create the Nessie Client object, which is inconvenient.

Nessie Client libs should support refreshing tokens on the fly.

[snazy]

@dimas-b should we consider this one for API v2?

[dimas-b]

I do not think this issue is particular to Nessie API v2 in the sense of REST paths and parameters. We're not changing how tokens are passed to the server.

I think this is more about the java client being able to refresh the token and then feed it into new API calls.