Registry collector to expand OCI collector

[pxp928]

Implementation of a registry collector, where the collector would query for all repositories and pull all metadata stored for each, was put on hold as _catalog API is not implemented the same across all registries. This would result in fixes and bugs depending on which registry (cloud or private) the user utilized. Each cloud-hosted registry adds its own custom API for listing things within a single org. We can revisit this later if needed but oci collector is currently setup such that it can be called by an upstream "registry collector" to collect from all repos in a registry in the future if needed. This can be done by the following using regclient API:

   repoTags := map[string][]string{}
   r, err := ref.New(o.registry)
   if err != nil {
     return fmt.Errorf("failed to parse ref %s: %v", r, err)
   }
   defer rc.Close(ctx, r)

   rl, err := rc.RepoList(ctx, o.registry)
   if err != nil && errors.Is(err, types.ErrNotImplemented) {
     return fmt.Errorf("registry %s does not support underlying _catalog API: %w", o.registry, err)
   }

   for _, repo := range rl.Repositories {
     r, err := ref.New(repo)
     if err != nil {
       return err
     }
     collectedTags, err := rc.TagList(ctx, r)
     if err != nil {
       return err
     }
     repoTags[repo] = collectedTags
   }

   ociRepoCollector := NewOCIRepoCollector(ctx, repoTags, false, time.Second)
   ociRepoCollector.RetrieveArtifacts(ctx, docChannel)
   o.checkedDigest[repo] = ociRepoCollector.checkedDigest
   return nil