update broadcast provider message status on success/error

so we can distinguish errorring messages that are currently retrying
from those that sent succesfully.

app/dao/broadcast_message_dao.py

@@ -61,3 +61,8 @@ def create_broadcast_provider_message(broadcast_event, provider):
         db.session.add(provider_message_number)
         db.session.commit()
     return provider_message
+
+
+@transactional
+def update_broadcast_provider_message_status(broadcast_provider_message, status):
+    broadcast_provider_message.status = status