Implement proper use of the 'origin' column during authentication.
This is to prevent authentication or non UAA users by the UAA authentication manager.
Refactor the authz_approval table to use USER_ID rather than non unique username
We will be having all users with origin=unknown. We can change those users to become origin=uaa when we authenticate them successfully.
This is the only safe way to make sure we mark the correct users with uaa, as we have no way of identifying their origin upon migration.