Switch `coffee-script` and `babel` to new compiled languages plugin

Now that we have a good way to compile source code into binaries, we should update the `coffee-script` and `babel` code paths to use the new compiled language plugin / API.

The main reason for this change will be unifying the code paths for compile / transpile steps and being able to use the new provider API and shasum checksums.

Medium priority as current performance seeks OK.