Use application_role_id on environment_roles.

In the future, an `application_invitation1 will not refer to a `user` until
someone accepts the invitation; they'll only reference an
`application_role`. When a user is invited to an application, the
inviter can specify the environments the invitee should have access to.
For this to be possible, an `environment_role` should reference an
`application_role`, because no `user` entity will be known at that time.

In addition to updating all the models and domain methods necessary for
this change, this commit deletes unused code and tests that were
dependent on `environment_roles` having a `user_id` foreign key.

tests/factories.py

@@ -163,20 +163,6 @@ class ApplicationFactory(Base):
         with_environments = kwargs.pop("environments", [])
         application = super()._create(model_class, *args, **kwargs)
 
-        # need to create application roles for environment users
-        app_members_from_envs = set()
-        for env in with_environments:
-            with_members = env.get("members", [])
-            for member_data in with_members:
-                member = member_data.get("user", UserFactory.create())
-                app_members_from_envs.add(member)
-                # set for environments in case we just created the
-                # user for the application
-                member_data["user"] = member
-
-        for member in app_members_from_envs:
-            ApplicationRoleFactory.create(application=application, user=member)
-
         environments = [
             EnvironmentFactory.create(application=application, **e)
             for e in with_environments
@@ -200,9 +186,14 @@ class EnvironmentFactory(Base):
 
         for member in with_members:
             user = member.get("user", UserFactory.create())
+            application_role = ApplicationRoleFactory.create(
+                application=environment.application, user=user
+            )
             role_name = member["role_name"]
             EnvironmentRoleFactory.create(
-                environment=environment, role=role_name, user=user
+                environment=environment,
+                role=role_name,
+                application_role=application_role,
             )
 
         return environment
@@ -234,7 +225,7 @@ class EnvironmentRoleFactory(Base):
 
     environment = factory.SubFactory(EnvironmentFactory)
     role = random.choice([e.value for e in CSPRole])
-    user = factory.SubFactory(UserFactory)
+    application_role = factory.SubFactory(ApplicationRoleFactory)
 
 
 class PortfolioInvitationFactory(Base):