OrgBook overwrites credential config with existing cache, if updated by the issuer

[ianco]

If the issuer updates a credential configuration (i.e. mapping info), OrgBook will squash the updates with a previously cached version of the credential type.

This is not expected behaviour (expected is that OrgBook will update its cache with the updates from the issuer)

Current state is that we must restart OrgBook if any updates are received from the issuer, after the issuer updates the config but before the issuer issues any new credentials