fix: windows shell

[Eomm]

The snippet in example.js doesn't work on windows platform with this setup:
(from git-bash)

echo $PATH
/mingw64/bin:/usr/local/bin:/usr/bin:/bin:/c/Program Files/Microsoft VS Code/bin
echo $EDITOR
code
echo $COMSPEC
C:\WINDOWS\system32\cmd.exe

For what I read from docs, this is caused by windows that require some adjustments on the spawn command in order to works properly:

• based on the editor, there should be a "binary windows" that could be:
  childProcess.spawn(${result.binary}.cmdorchildProcess.spawn(${result.binary}.exe
• the easiest is this PR, that add shell: process.platform === 'win32' parameter so the command will be executed in a standalone shall

A related issue on node.js (since vscode is an electron app)
nodejs/node#15217

I would appreciate your thought about this PR.
Thank you very much

[sindresorhus]

Using the shell option is almost always the wrong answer. You could maybe try using https://github.com/sindresorhus/execa instead of child_process.spawn here and see if that fixes it. That module have many things to make it work better on Windows.