Send transitive module dependencies in the compiler response

Currently the loader works by discovering dependencies as it loads them. If the server sent all transitive dependencies in the response, we could more efficiently load resources since we know ahead of time what we need to request.

The issue names no files or tests; start by tracing the loader and the server's compiler response to understand where dependencies are currently discovered. Done means the response includes all transitive module dependencies so the loader can know which resources to request before loading them.