Provide a way to automatically add license headers

We periodically see repos being donated to the kubernetes org(s). Donation requires these repos to add boilerplate license headers to all their files. Today, we don't have a way to do this automatically.

https://github.com/kubernetes/repo-infra/pull/82 took a dab at this but was closed due to age.

@dims also pointed a few other alternative approaches:

1. https://github.com/kunalkushwaha/ltag - this is used in containerd
2. https://github.com/google/go-licenses

/help