Add some OIDC flow tests.

Enable testing for gregui, add a django config for testing.

gregui/authentication/auth_backends.py

@@ -205,7 +205,6 @@ class GregOIDCBackend(ValidatingOIDCBackend):
         person, _ = Person.objects.update_or_create(
             first_name=userinfo["first_name"],
             last_name=userinfo["last_name"],
-            email=userinfo["email"],
         )
         person.save()
         return person
@@ -242,6 +241,17 @@ class GregOIDCBackend(ValidatingOIDCBackend):
                 )
                 identity.save()
 
+            try:
+                email_identity = Identity.objects.get(
+                    type="private_email", value=userinfo["email"]
+                )
+            except Identity.DoesNotExist:
+                # Add email if missing
+                email_identity = Identity(
+                    type="private_email", value=userinfo["email"], person=person
+                )
+                email_identity.save()
+
             user_profile = GregUserProfile(
                 user=user,
                 person=person,