Move the logging setup into a function

It'd be useful if the code that configures a lambda-friendly logger was in a standalone function so it could be used by code in `chalicelib` that doesn't need a dependency on a chalice app.

Locate the existing code that configures the Lambda-friendly logger and read how it depends on a Chalice app. Extract that setup into a standalone function usable from chalicelib without an app dependency; done when callers can use the function independently and existing logging behavior remains intact.

Written by the indexing model from the issue text.