Compile with TSC SolutionBuilder (#1239)
Changes build tooling to use TSC's native project references for building. Unfortunately this makes full builds slower but incremental builds are much faster.
Also somewhat unfortunately I moved codegen of "proxies" (calling them "forwards" now) to work like our other codegen does, so they now need to be updated and commited to git. Couldn't get the build-time approach to work with SolutionBuilder, hit a bug and limits of API flexibility.
I added code to skip build for projects entirely if files are not dirty and the .d.ts files of dependencies have not changed (based on SHA-1 checksums).
Includes various small improvements to tooling.
