make-generated-{protobuf,runtime}.sh was doing some really nasty stuff with how
the build container was managed in order to copy results out. Since we have
more flexibility to grab results out of the build container, we can now avoid
all of this. Ideally we wouldn't have `hack` calling `build` at all, but we
aren't there yet.
We also add "version" to all docker images and containers
This version is to be incremented manually when we change the shape of the build
image (like changing the golang version or the set of volumes in the data
container). This will delete all older versions of images and containers when
the version is different.
