How to Dynamically Provide Region to Layers

### Amplify CLI Version

12.1.0

### Question

I have a function added through `amplify add function` in which I specify the AWS Lambda Powertools layer (Python). When providing the lambda layer ARN I have to hardcode the layer region as part of the layer ARN. Is there a way that we can use template variables in the layer ARN i.e. AWS::Region?

For reference, the layer ARN in question is `arn:aws:lambda:{region}:017000801446:layer:AWSLambdaPowertoolsPythonV2:34`

Start with the `amplify add function` flow and the configuration that accepts the AWS Lambda Powertools Python layer ARN. Check whether template variables such as `AWS::Region` are supported there; done means the layer ARN can use the deployed region without hardcoding it, with the behavior verified in the relevant CLI tests.

Written by the indexing model from the issue text.