Description of problem:

Right now the skope-copy task doesn't support authentication via auth-file, only via using a basic-authentication secret.

There are already quite a few tasks which actually support using an auth-file (f.e. buildah).

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. Create a skopeo-task

2. Try to copy an image from an external registry with no authentication secret with this task

Actual results:

Can't configure skopeo-copy task to use an auth-file/dockerjson-config file to configure authentication for container registries

Expected results:

I can pass a dockerconfig-secret  containing the "auth.json" file to the skopeo-copy task

Reproducibility (Always/Intermittent/Only Once):

Always

Acceptance criteria: 

Authentication via dockerconfig file is working.

Definition of Done:

Build Details:

Additional info (Such as Logs, Screenshots, etc):

 *