Fix extension development to work on Windows

[matthewbastien]

Description

Get npm install to work properly on Windows:

• Remove the dependency on node-pty and include only its typings file instead.
• Revert back to [email protected] since newer versions don't work on Windows.
• Properly invoke npm and npx on Windows inside our TypeScript scripts by using npm.cmd and npx.cmd respectively.
• Disable the linebreak-style ESLint rule when building swift-docc-render as it was erroring out on pretty much every file.
• Stop using npm's -ignore-scripts option in CLI to catch problems before they're merged.

Issue: #1854

Tasks

• Required tests have been written
• [ ] Documentation has been updated
• [ ] Added an entry to CHANGELOG.md if applicable