Capturing and showing stdout / stderr

## Expected Behavior
When specifying stdout / stderr logs for steps within the workflow it works as expected and all stderr and stdout is captured.

However I would opt for an option to also have it shown to stdout / stderr in the terminal. This makes identifying issues easier when debugging. For example when using the debug mode it could always prompt to the screen and when present in the cwl also write to the log files or a new option could be added.

## Your Environment
* cwltool version: 3.0.20200416192244

I had ticket regarding capturing stdout in https://github.com/common-workflow-language/cwltool/issues/1156 which I closed as it works as expected.