Enabled AWS Lambda Support and Deployment steps

[ben-fletcher]

Summary

Allow the web-api backend to be ran in a serverless lambda function in AWS

Current Behavior

Web api can only be ran on a server or as a docker container on a server.

Expected Behavior

Web api should be able to run on server and serverless technology.

1. This means creating a lambda entry point class
2. Building api gateway and lambda stack in AWS
3. Adding deployment steps to pipeline to deploy to existing AWS Lambda function

NOTE: To start with, the api lambda function will run in parallel to the existing production ecs task. This allows for extensive testing in the production environment before switching the production site over to using the severless api. Finally the front end will need to be migrated over to be statically hosted as they no longer rely on it's own backend