support TypeScript debugging with dev-server

[AlCalzone]

Works for me now. The Webstorm users will need to translate the launch.json to something Webstorm understands. Probably needs the "remote urls for local files" setting here: https://www.jetbrains.com/help/webstorm/run-debug-configuration-node-js-remote-debug.html#ws_node_specific_attach_to_chrome_settings

[AlCalzone]

Let's make this a draft until we can reference a published dev-server version that supports this.