Jib should avoid parallel image downloads for same image

Although jib is thread-safe, it should be smarter.

Jib doesn't currently lock the base image cache when downloading a base image, but instead downloads into a temporary directory and then attempts to moves the downloaded image into place. There is no locking to block other threads. So a Maven project with _N_ modules that build images using the same base image (like `gcr.io/distroless/java`) may result in _N_ simultaneous pulls of the same image. Maybe we should provide a component to centralize downloading images?

_Originally posted by @briandealwis in https://github.com/GoogleContainerTools/jib/issues/1904#issuecomment-521352655_