celery: broadcast msg create invokes cbc proxy

When we create a broadcast message, we should invoke the cbc proxy to
send a cap message

Either a function will be invoked within AWS, or a noop function call
is made, depending on the environment

We have only implemented CB message creation in the CBC Proxy, without
polygons, therefore we:
* only invoke the CBC Proxy during message creation
* only send description, identifier, and hard-coded headline

Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
Co-authored-by: Pea <pea.tyczynska@digital.cabinet-office.gov.uk>
Co-authored-by: Katie <katie.smith@digital.cabinet-office.gov.uk>

app/celery/broadcast_message_tasks.py

@@ -2,8 +2,9 @@ import requests
 from flask import current_app
 from notifications_utils.statsd_decorators import statsd
 
-from app import notify_celery
+from app import cbc_proxy_client, notify_celery
 
+from app.models import BroadcastEventMessageType
 from app.dao.broadcast_message_dao import dao_get_broadcast_event_by_id
 
 
@@ -12,6 +13,19 @@ from app.dao.broadcast_message_dao import dao_get_broadcast_event_by_id
 def send_broadcast_event(broadcast_event_id, provider='stub-1'):
     broadcast_event = dao_get_broadcast_event_by_id(broadcast_event_id)
 
+    if broadcast_event.message_type == BroadcastEventMessageType.ALERT:
+        current_app.logger.info(
+            f'invoking cbc proxy to send '
+            f'broadcast_event {broadcast_event.reference} '
+            f'msgType {broadcast_event.message_type} to {provider}'
+        )
+
+        cbc_proxy_client.create_and_send_broadcast(
+            identifier=str(broadcast_event.id),
+            headline="GOV.UK Notify Broadcast",
+            description=broadcast_event.transmitted_content['body'],
+        )
+
     current_app.logger.info(
         f'sending broadcast_event {broadcast_event.reference} '
         f'msgType {broadcast_event.message_type} to {provider}'