As an OpenShift user
I want to push manifest lists into the image registry
so that I can mirror manifest lists into the registry and use them.

Acceptance criteria

• Users can push manifest lists
• Users can push an image by SHA (via skopeo or oc image mirror)
• Partially pushed manifest list (i.e. images that pushed by SHA) shouldn't be immediately pruned
• Images that are pushed by SHA can be pulled by SHA
• If a manifest list is tagged (via `oc tag`) into another namespace, it should be able to pull it from that namespace