Build separate various binary tarballs

Also a bunch of script clean up.  Make make-clean.sh faster and more robust.

Building the docker run images and uploading to GCS are now optional and turned off by default. Doing a release shouldn't hit the network now (I think).
You could drop one of these mkdir's since `mkdir -p "${release_stage}/platforms"` will also create the `${release_stage}` directory.

Or, if you want to keep them as separate commands, you could drop the `-p` from the second command since you're creating a single directory in that case.