Consolidates project loading code from kmc and kmc-copy, in preparation
for kmc-test epic. This leaves open a change we need to make to
CompilerCallbacks, to consolidate the fsAsync and net callbacks into
CompilerCallbacks as a first-class part of CompilerCallbacks. We will
then need to start to move all the fs and net callback interactions to
the async model across all kmc modules, at some point.