During the collector phase it is needed to check if the manifest of the operator catalog and release in the remote mirror registry is the same as the one currently in the cache, if it is not download all the latest content and add it to the cache.

Acceptance criteria:

• I should be able to mirror from 2 catalogs without the content of working-dir/operator-images/redhat-operator-index or working-dir/hold-operator/redhat-operator-index of 1 catalog replacing the other (already covered AFAIK)

  mirror: 
    operators: 
    - catalog: redhat-operator-index:v4.12
    - catalog: redhat-operator-index:v4.13
  

• In the event of z-stream release of v4.12, I want oc-mirror to detect there is a new image to pull from registry, and not rely on the existance of folder working-dir/operator-images/redhat-operator-index/v4.12 or working-dir/hold-operator/redhat-operator-index/v4.12 as a reason not to get the fresh digest for this tag

  mirror: 
    operators: 
    - catalog: redhat-operator-index:v4.12