Add an endpoint to delete a contact list

This was one of things we de-scoped when we first shipped this feature.

In order to safely delete a list, we first need to make sure any jobs
aren’t referencing it.

app/dao/jobs_dao.py

@@ -135,6 +135,14 @@ def dao_update_job(job):
     db.session.commit()
 
 
+def dao_unlink_jobs_from_contact_list_id(contact_list_id):
+    Job.query.filter(
+        Job.contact_list_id == contact_list_id,
+    ).update({
+        'contact_list_id': None,
+    })
+
+
 def dao_get_jobs_older_than_data_retention(notification_types):
     flexible_data_retention = ServiceDataRetention.query.filter(
         ServiceDataRetention.notification_type.in_(notification_types)

app/dao/service_contact_list_dao.py

@@ -23,3 +23,8 @@ def dao_get_contact_lists(service_id):
 def save_service_contact_list(service_contact_list):
     db.session.add(service_contact_list)
     db.session.commit()
+
+
+def dao_delete_contact_list(service_contact_list):
+    db.session.delete(service_contact_list)
+    db.session.commit()