The Go dependency is still required to build the pack binary.
Use "tilt docker" to use Minikube's Docker instance, if available,
removing the local Docker dependency for Minikube users.
The Makefile continues to not require Docker and runs buf locally.
Remove broken Powershell scripts (can't test on Windows). These scripts
should now be substantially easier to write.
Change-Id: Ie80bf68e0e468a747861bea36fa5b353d9de110d
Leo