Describe the story

Add a utility helper module for interaction with the AWS SDK SNS client. Add a function to publish messages to a SNS topic.

Acceptance criteria

GIVEN the app needs to publish a SNS message
WHEN the application imports the SNS client
THEN the AWS SDK SNS client instance is created
AND the AWS SDK SNS client is configured
AND the AWS SDK SNS client instance is stored as a module constant to be preserved between Lambda invocations

WHEN the application uses the "publish" function
THEN the AWS SDK SNS client instance is used to publish a message
AND the message is published on a specific topic
AND all supplied message attributes are included

Additional context

Add any other context about the story here.