Add support for selecting Architecture to Deploy function to

AWS began supporting Graviton2 processors today:

https://aws.amazon.com/blogs/aws/aws-lambda-functions-powered-by-aws-graviton2-processor-run-your-functions-on-arm-and-get-up-to-34-better-price-performance/

It would be great if we could select the architecture we want to deploy the code we are using to in the config.json file.

Start by tracing how config.json is parsed and how the deployment request selects Lambda function settings. Add a way to choose the deployment architecture in config.json, then verify that the selected architecture is passed through to the deployed function and covered by the relevant tests.

Written by the indexing model from the issue text.