oc-mirror support for multi-arch filtering

1. Proposed title of this feature request

oc-mirror supports multi-arch filtering to decrease download time & data volume

2. What is the nature and description of the request?

oc-mirror should provide an option to let the user select the compute architectures they are targeting run in their disconnected environment. This allows them to save time and storage space to prepare and update the disconnected registry mirrors.

In particular oc-mirror should make use of the functionality described in PROJQUAY-3114 which is based on spec changes in OCI and Docker image specifications. oc-mirror should push manifest lists unchanged so that their digests do not differ from the source but should omit pushing child manifests which do not correspond to a list of desired compute architectures in the oc-mirror config file.

3. Why does the customer need this? (List the business requirements here)

Most customers in disconnected pay a premium for storage space. At the same time they are wasting storage space with the current implementation of oc-mirror because it has to mirror all manifest list (multi-arch) images including all child manifests / images which significantly increases the storage consumption. They very often only have a single compute architecture but have to account for storage space for all of OCPs supported compute architectures.
Only storing the images that correspond to the actually required compute architectures the customers have will significantly reduce the amount of registry mirror storage and download time required to main disconnected copies of OCP core payload and optional operator images.
4. List any affected packages or components.