unsetDid for the client when logging out

[pradel]

Description

In order to authenticate with composeDB we do the following to authenticate the requests.

composeClient.setDID(did);

When logging out there is no way to unset the did and do the next request as an unauthenticated user. It would be very handy to be able to do one of the following.

composeClient.setDID(null);
composeClient.unsetDid();

For now as a workaround I am doing the following

composeClient.setDID(null as any);