launch config for attach shows squiggles 'showReturnValue' option

[karthiknadig]

Environment data

• VS Code version: 1.30.1
• Extension version (available under the Extensions sidebar): 2018.12.1
• OS and version: Any
• Python version (& distribution if applicable, e.g. Anaconda): Any
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): Any
• Relevant/affected Python packages and their versions: Any

Expected behaviour

Should not show squiggles and allow setting that option for attach.

Actual behaviour

[DonJayamanne]

Prescribed solution:

• Modify package.json to add this
• Update VSC docs (create issue to get this documented).

[qubitron]

@karthiknadig can we just have this on by default? Is there a reason we need a setting to disable it?

[karthiknadig]

This can be ON by default.