Epic: As an administrator when I configure user federation and identity brokering with IAM server I don’t want to persist any user information in Keycloak database. Using only corporate LDAP or external IdP for user storage and not copying any information to Keycloak database.

Context: This request comes very frequently from number of sources. Internal projects, community and other side conversations. When KC is being used as a bridge between external IdP and application our users don't want to introduce yet another user store. Support for this will come with some limitations - as storing users within KC in such scenarios comes with a reason.