Goal: As a Quay user I want to be able to apply filters to multi-arch images so that I can reduce the amount of data being copied when using repo mirroring with multi-arch images.

Background: Currently repo mirroring is driven off lists / expressions of image tags that define the set of images to be mirrored. A user cannot filter unwanted architectures of multi-arch images today.

Why is this important: In many cases today images are actually manifest lists, with child manifests per compute architecture of the software contained (e.g. x86_64, arm64, ppc64le, etc). Often users however require only a specific set or single architecture for the image images in question. Filtering for those significantly in a mirroring job significantly reduces the amount of data copied of the network, thus speeding up the overall mirroring process. It also requires less storage inside Quay, since multi-arch images typically don't share common layers and thus Quay's layer deduplication is not effective with multi-arch images and storage consumption grows. Finally, less images means also less scanning for Clair, which due to the lack of layer sharing between multi-arch images otherwise has to scan more images and thus consume more system resources.