Docker authentication for AWS

[alexeagle]

Trying

oci_pull(
    name = "aws_lambda_python",
    # tag = "3.8"
    digest = "sha256:46b3b8614b31761b24f56be1bb8c7ba191d9b9b4624bbf7f53ed7ddc696c928b",
    image = "public.ecr.aws/lambda/python",
)

which fails

Error downloading [https://public.ecr.aws/v2/lambda/python/manifests/sha256:46b3b8614b31761b24f56be1bb8c7ba191d9b9b4624bbf7f53ed7ddc696c928b] to /shared/cache/bazel/user_base/31d1af6682b925f850635e639ebdf8e8/external/aws_lambda_python/46b3b8614b31761b24f56be1bb8c7ba191d9b9b4624bbf7f53ed7ddc696c928b: GET returned 401 Unauthorized

From https://docs.aws.amazon.com/AmazonECR/latest/public/public-registries.html#public-registry-auth I guess there is something we have to do, I'm not sure if it's covered by current Work-in-Progress or not.