Add LDAP filter option for specifying external users
Currently, LDAP group sync will manage external users based on specific groups in LDAP. A customer is currently managing external users via the API rather than using LDAP group sync because they need to rely on one or more user attributes to determine external or not.
We could improve the group sync option by allowing administrators to specify a filter for external users. This would open things up similar to the LDAP group link filter did recently - users could specify a filter that includes individual users, or attributes of users, etc. The implementation would be much easier since this would be a config file based change and not a UI.
cc/ @stanhu