Don't output to stdout directly

**Is your feature request related to a problem? Please describe.**
When the handlers returns any non-nil error, `reportFailure` is called and it does a [raw log.Printf](https://github.com/aws/aws-lambda-go/blob/main/lambda/invoke_loop.go#L106) call, outputting a line in the standard go format like `2023/07/10 20:12:21 {"errorMessage":"error"}`, breaking our logs handling which expects all logs to be JSON.

**Describe the solution you'd like**
Libraries should not output to stdout, at least a logger should be configurable.

**Describe alternatives you've considered**

**Additional context**