escape backslash in args

[ousttrue]

Hello.

Backslash in args require escape.

// launch.json.
            "args": [
                "C:\\GLtfSampleModles\\2.0\\Cube\\glTF\\Cube.gltf",
            ],

This pull request escape backslash.

src.replace(/\\/g, "\\\\");

Thank you.

[tomblind]

Thanks for submitting this! Your fix worked in windows but didn't resolve the issue in linux, so I pushed an alternative solution that works in both: 567607b

I'll try to submit a new version to vscode soon which will contain this fix.