Have permissions decorators check user signed in

Rather than force us to write the decorators in a specific order let’s
just have one decorator call the other. This should make fewer lines of
code, and fewer annoying test failures. It also means that the same way
of raising a `401` (through the `current_app` method) is used
everywhere.

tests/app/models/test_user.py

@@ -1,6 +1,17 @@
 import pytest
 
-from app.models.user import User
+from app.models.user import AnonymousUser, User
+
+
+def test_anonymous_user(app_):
+    assert AnonymousUser().is_authenticated is False
+    assert AnonymousUser().logged_in_elsewhere() is False
+    assert AnonymousUser().default_organisation.name is None
+    assert AnonymousUser().default_organisation.crown is None
+    assert AnonymousUser().default_organisation.agreement_signed is None
+    assert AnonymousUser().default_organisation.domains == []
+    assert AnonymousUser().default_organisation.organisation_type is None
+    assert AnonymousUser().default_organisation.request_to_go_live_notes is None
 
 
 def test_user(app_):