process letters from api traffic

there are three steps to this

1. Create a job
  * Starts in status 'ready to send'
  * Created by None, since it's from the API
  * original file name 'letter submitted via api'
2. Create a single notification for that job
  * job_row_number 0
  * client reference if provided
  * address line 1 as recipient
3. Trigger the build_dvla_file task
  we know that all the notifications have been created for this job
  (since we just created them ourselves synchronously), so this will
  just create the dvla-format file for the job, and upload it to s3.

app/notifications/process_notifications.py

@@ -55,7 +55,7 @@ def persist_notification(
     created_by_id=None
 ):
     notification_created_at = created_at or datetime.utcnow()
-    if not notification_id and simulated:
+    if not notification_id:
         notification_id = uuid.uuid4()
     notification = Notification(
         id=notification_id,