Deploy time Secrets Manager support needed

This is referencing back to #811 that has been closed.
I would like to make an argument that this is an essential feature to be supported at deploy time by Chalice.
**Security concern:** In order for deployed lambda to be able to retrieve keys from Secrets Manager it requires various kind of elevated permissions to be used at execution time. This problem is alleviated if values are pulled from Secrets Manager at deploy time using Admin credentials of the user performing the deployment or a CI process and turned into environment variables.
I am observing this complication with every Lambda I build and I find it suboptimal to consistently increase attack surface of my solution.

Start by reviewing the closed issue #811 and its discussion for prior requirements or decisions. Then examine Chalice's deployment flow and how Lambda environment variables and AWS credentials are handled; done means defining secure deploy-time Secrets Manager retrieval without requiring those permissions at runtime.

Written by the indexing model from the issue text.