[keycloak-dev] turning import on/off implications

[Bill Burke]

When it is finished, you will be able to choose whether LDAP provider 
imports users or not.  The thing is, if you run with import On (which 
will be the default setting for older migrated ldap deployments)...then 
you switch it to OFF what should happen? My first thought is that we 
remove all imported users when that switch is fllicked off.  This would 
require:

* an onUpdate(ComponentModel old, ComponentModel new) callback to the 
UserStorageProvider so it can trigger deletion.

* A method deleteLinkedUsers(String federationLink) on userLocalStorage()

I'm also wondering if the generic console should have a 
DELETE_LINKED_USERS and UNLINK USERS button if the provider supports import.

See any problems with this?