Add alert for failed events after retry and fix broken cloud event exception handling

Relates #3 (closed)

terraform/modules/faas/main.tf

@@ -180,3 +180,10 @@ resource "google_pubsub_topic_iam_member" "publish_deadletter_topic" {
   role   = "roles/pubsub.publisher"
   member = "serviceAccount:${google_project_service_identity.pubsub_agent.email}"
 }
+
+
+resource "google_pubsub_subscription_iam_member" "deadletter_subscribe" {
+  subscription = google_pubsub_subscription.provided_topic[0].name
+  role         = "roles/pubsub.subscriber"
+  member       = "serviceAccount:${google_project_service_identity.pubsub_agent.email}"
+}