As of today users can use globs to filter a subset of a repository content to be mirrored via rep mirroring. This works fine for mirroring into the primary registry but given the immutability of the mirrored repo the user can't do a second, more fine granular and customized mirroring operation such as for env promotion. If the tags inside the mirrored repo are immutable we should allow to add labels. If in addition to tags we can filter by labels we would better support content staging operations within the same registry or across multiple Quay deployments.