Switch ampx sandbox for the ampx pipeline-deploy

https://github.com/aws-samples/agents4energy/blob/4d437d1c87d112776463f22079ddacfe30e9d37a/scripts/build.sh#L3-L13

Currently the aws amplify project is deployed in sandbox mode. This is not the correct mode for a production application. Add a small cloudformation deplyment to produce an amplify app, and feed that app id into the build script so that it can be referenced in the ampx deploy-pipeline call.

The deletion scripts should also be updated to delete the amplify app when the delete operation is called.