Login auth

This should allow login via UUID if set correctly. 

You will need the following in your saml.php settings for this to work
```
'internal_id_property' => 'uuid',                                                         
'saml_id_property' => 'UUID',                                                             
'object_mappings' => [                                                                    
   'email' => 'email',                                                                    
],  
'can_create' => false,                                                                    
'can_create_error' => 'The authorising UUID is not in this system\'s database - check you are authenticating against this database', 
```

Then you should be able to log in to backoffice and it will use UUID, you can check this if you login to a local environment with a user that is only present on the control one. It should be created with the same UUID and email on your local.