Reconsider how the Generated Code occurs

[mwpowellhtx]

We are more or less a third, perhaps one half, of the way there, we think. Consider instead of invoking a code generation asynchronously, that the service yields to a reactive, observable collection of CompilationUnitSyntax elements. Upon each element being generated, that is when we would do such things as write the generated code to file, register said generated code with the internal registries for bookkeeping, and so on.