Reduce storage requirements for mirroring a 4.7 catalog

1. Proposed title of this feature request

Reduce storage requirements for mirroring a 4.7 catalog

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

The current mapping.txt generated by oc adm catalog mirror --manifest comes out to 4,155 images. These are upwards of 900-1000 GB in size.

 opm index prune doesn't support pruning down to specific versions and the bundle paths which don't even exist for all operators like kubevirt, still have all the versions in them. 

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

We need to be able to pull a catalog, isolate a specific version of an operator and pull ONLY those images to minimize storage usage.

4. List any affected packages or components.

OpenShift 4.7

• OLM