[ALOY-1612] CLI: Be able to use Alloy source-maps in Safari Debugger / Chrome Dev-Tools

Based on a recent discussion with [~cbowley]! Currently, when debugging Alloy in Safari / Chrome, the dev-experience is pretty bad, because the developer sees the generated spaghetti code instead of the actual Alloy code. But there is help! We generate proper [source-maps](https://www.html5rocks.com/en/tutorials/developertools/sourcemaps/) already (look into build/map/*, but it seems like they are not actively used. In addition, it seems like they are indeed used during compile time - for compilation errors when using Babel, where they are doing a great job in indicating the actual line number and character of the error. If we could adapt source-maps to the Safari- and Chrome-debugger, we could enable a whole new debugging experience, e.g. by integrating it into our editor plugins and be able to create web-based debuggers like some others do. Thoughts welcome!