Container Support

Ticket moved to GitHub: "pulp/pulp_container/474":https://github.com/pulp/pulp_container/issues/474

A manifest list/image index can contain multiple image manifests that are build for different platforms/os. Enable use case when a specific platform is needed to be mirrored instead of mirroring everything.

Specify the preference in the remote config . This option will not be compatible with the mirror set to True.

For pulp2pulp sync and pass-through sync Loosen up the manifest download validation, do no fail all manifest download if we get 404 on one of the image manifests.

Dockerhub --> Pulp1(mirror selected platforms from image index )-->Pulp2(mirror all from image index) In case of pass-through Pulp2 will get 404 on everything what was filtered out in Pulp1(do not fail the sync, continue with what's available). The previously selected content in Pulp1  would pass through the request and download of images/blobs would happen from Dockerhub and passed to Pulp2.