Ability to distinguish creation events for synchronisation-created users

When users are created as part of external directory synchronisation, it would be nice if there was a way to determine this from the event fired.

In Studio, users can be created from three sources: manual creation from the UI, creation as part of synchronisation with Google, and creation as part of synchronisation with an external directory. In the first case, application access is granted according to the choices made by the creating admin. In the second case, default application access is granted when the user first logs in. In the third case, however, currently no application access is granted, leaving the users unable to login with the manual intervention of an administrator.

Allowing us to determine that a UserCreatedEvent was fired due to external directory synchronisation creating a user would allow us to assign default application access to users in this third situation. Note that simply assigning default access to a user on receipt of a UserCreatedEvent would not work, as the users created by Google synchronisation for customers with large Google domains would exhaust their application license counts.