publish multi-arch manifest to ECR

[rittneje]

We would like to request that AWS start publishing a multi-arch manifest (aka "shared tags") for the "public.ecr.aws/aws-iot-securetunneling-localproxy/debian-bin" and "public.ecr.aws/aws-iot-securetunneling-localproxy/ubuntu-bin" images.

Currently the "latest" tag for these images seems to refer to a totally arbitrary platform. For example, "public.ecr.aws/aws-iot-securetunneling-localproxy/debian-bin:latest" currently refers to a linux/amd64 image, while "public.ecr.aws/aws-iot-securetunneling-ocalproxy/ubuntu-bin:latest" currently refers to a linux/arm image.

Instead, when I pull the "latest" tag for either of those images, it should automatically resolve to the image that matches my architecture. I should not need to explicitly specify "arm64-latest" or "amd64-latest". This would make it much easier to have universal instructions for our developers.