Add a local private image repository for multiplatform images

[andresrinivasan]

It's annoying that in order to use a multiplatform image, it needs to be pushed to a private image repository, usually remote. I would like to be able to build and test a multiplatform image locally before I push it.

[kdrag0n]

This is blocked on the upstream Moby project. OrbStack will support it as soon as it's viable.