Add app push call and infra Reliability call to Notifications

[thiessenp-cds]

At this point the Notifications lambda is ready to be used. Update the app code to send a push message to the Notifications lambda on a form submission. The push call should be wrapped as a reusable lib call. Also update the infra Reliability lambda to call the SQS Notifications when a submission has finished processing and a notification should be sent.

From the architecture diagram, the related work is in green: