vsce should package closure without devDependencies

[heaths]

Using mainly the default generated files from generator-code, a significant number of devDependencies (mostly recursive) are pulled in - mainly because of Mocha. For development this is fine (I love Mocha). But why blindly package them all with vsce package? Perhaps create an output directory of everything vsce ls would find but node_modules, then run npm install --production and package that directory. Would certainly reduce the size of VSCode extensions. Mine - with only the addition of 1 small module (with no dependencies itself) is over 5MB.

[joaomoreno]

Duplicate of microsoft/vscode-vsce#52