Include credential helper binaries in Docker image for crane

It would greatly ease using crane in a CI/CD pipeline if it was able to make use of the credential helpers mentioned in https://github.com/google/go-containerregistry/tree/master/pkg/authn

As it stands, you need to use another method to get the login credentials into the running container. Not a hard problem to solve, but not as elegant as using credential helpers, which is the recommended way anyway.

Kaniko bundles the common helpers (AWS, GCP) in, so it seems feasible to bundle them in to the official Crane docker image too.

Start with the official Crane Docker image and the credential helpers listed in pkg/authn. Determine how the common AWS and GCP helpers should be bundled, then verify that the resulting image can use them for authentication in a CI/CD container.

Written by the indexing model from the issue text.