Audit logs: Show projects for services

Before, when displaying the audit logs for services, there was no information
regarding when a project was added on a service, or modified, or deleted.

That information is useful when tracking things down while debugging, so let's
add it.

promgen/models.py

@@ -210,6 +210,7 @@ class Service(models.Model):
     )
 
     notifiers = GenericRelation(Sender)
+    project_set = GenericRelation("Project")
     rule_set = GenericRelation("Rule")
 
     class Meta:

promgen/views.py

@@ -230,6 +230,12 @@ def get_queryset(self):
                         content_type_id=ContentType.objects.get_for_model(models.Rule).id,
                         object_id__in=obj.rule_set.values_list("id", flat=True),
                     )
+                if key == "service":
+                    # Only services may have projects
+                    qset |= Q(
+                        content_type_id=ContentType.objects.get_for_model(models.Project).id,
+                        object_id__in=obj.project_set.values_list("id", flat=True),
+                    )
                 if key == "project":
                     # Only projects may have exporters
                     qset |= Q(