Keycloak Operator doesn't provide a way to configure User Federation with LDAP. Since Keycloak REST API does it, we should also provide this in the Operator for symmetry.
KeycloakAPIRealm should reflect RealmRepresentation. The goal is to add userFederationProviders sub-resource to the KeycloakAPIRealm. No other changes should be necessary.
2-3 days for 1 person.