Automatic merge from submit-queue

Start making `k8s.io/client-go` authoritative for generic client packages

Right now, client-go has copies of various generic client packages which produces golang type incompatibilities when you want to switch between different kinds of clients.  In many cases, there's no reason to have two sets of packages.  This pull eliminates the copy for `pkg/client/transport` and makes `client-go` the authoritative copy.

I recommend going by commits, the first just synchronizes the client-go code again so that I could test the copy script to make sure it correctly preserves the original package.

@kubernetes/sig-api-machinery-misc @lavalamp @sttts