Address #321: Finegrained repo location patching.

Created by: garloff

So we copy the capi knowledge of whether kube-proxy is at the old location (k8s.gcr.io) or at the new one (registry.k8s.io). As the logic became somewhat involed, split it out into a separate script that can be tested more easily.

Signed-off-by: Kurt Garloff kurt@garloff.de