Have access to user information on deletion

In order to delete users on a third party IdP (like Okta), NOS needs to query Okta with an email address (connect username can't be used).

The user_deleted event is fired AFTER the user is actually deleted so the information is already gone, and we can't leverage it.
=> a suggested solution could be to fire a before_user_deleted event, containing the user information including the email address.

Currently, NOS is using a workaround by extending the UserManagerImpl to fire this event.