Automatic merge from submit-queue

If token validation fails, give the user the expected format.

If a user specifies their own token to kubeadm, and it fails validation, the error they currently receive isn't the friendliest. This first change adds messaging for the expected token format, with more improvements to follow as part of #33930. It also adds some unit tests to document the behavior we have currently.

CC: @mikedanese, @krousey, @kubernetes/sig-cluster-lifecycle

Part of #33930.