Notification if external user management is activated

A notification will be displayed when an external user
management system is activated to inform that users
created within the SCMM will not be transferred to the
external system.

Co-authored-by: René Pfeuffer<rene.pfeuffer@cloudogu.com>

scm-ui/ui-types/src/User.ts

@@ -47,7 +47,9 @@ export type UserCreation = User;
 
 export type UserCollection = PagedCollection<{
   users: User[];
-}>;
+}> & {
+  externalAuthenticationAvailable: boolean;
+};
 
 export type PermissionOverview = HalRepresentation & {
   relevantGroups: PermissionOverviewGroupEntry[];