Wire up variant and features for selecting images from manifest lists #22816
Description
From distribution: https://github.com/docker/docker/blob/master/distribution/pull_v2.go#L619
It would be great to get this wired up in engine so that images get OS variant metadata when built and if this were used when choosing an image from a manifest list.
This has applicability for Windows, where we need to disambiguate between images for Nanoserver and Windowsservercore.