Lage's own build does not produce SourceMaps

[dannyvv]

Describe the bug
Debugging Lage itself is not as easy as it could be.
The transpiler does not seem to emit SourceMap (.js.map) files to make the debug/edit loop super effecient...

To Reproduce
Steps to reproduce the behavior:

1. enlist and build lage repo
2. add launch.json with a section like:

3. put a breakpoint in the .ts file that should be hit...
4. Start the program

Expected behavior
Breakpoint to be hit. But it is not because there is no sourcemap (not for the .js file running with yarn watch nor for the bundle...

Troubleshooting
I tried adding sourcemaps: true to the .swrcc file but that flag only works for the entire compile unit and we are manually doing stuff file by file...
I tried reading the rust code, but it seems that the 'transform' function does not handle sourcemaps....