oc-mirror in a disconnected environment fails with a "HTTP 401 Unauthorized" error

Issue

• "oc-mirror" retrieves registry credentials from ~/.docker/config.json, that is inconvenient that a user is forced to add credentials to such a generic location for mirroring purposes. How can this path be defined in another way?

• When trying to run the "oc-mirror" plugin without having a matching registry credential in one of ${HOME}/.docker/config.json or ${XDG_RUNTIME_DIR}/containers/auth.json paths against a private Container Image Registry a 401 Unauthorized error is returned:

  $ ./oc-mirror --config imageset-config.yaml file://archive
  Creating directory: archive/oc-mirror-workspace/src/publish
  Creating directory: archive/oc-mirror-workspace/src/v2
  Creating directory: archive/oc-mirror-workspace/src/charts
  Creating directory: archive/oc-mirror-workspace/src/release-signatures
  backend is not configured in imageset-config.yaml, using stateless mode
  backend is not configured in imageset-config.yaml, using stateless mode
  No metadata detected, creating new workspace
  level=info msg=trying next host error=failed to authorize: failed to fetch anonymous token: unexpected status: 401 Unauthorized host=registry.redhat.ioThe rendered catalog is invalid.Run "oc-mirror list operators --catalog CATALOG-NAME --package PACKAGE-NAME" for more information.error: error rendering new refs: render reference "registry.redhat.io/<any-namespace>/<image-name>:<image-tag>": error resolving name : failed to authorize: failed to fetch anonymous token: unexpected status: 401 Unauthorized
  the command terminates with HTTP401 Unauthorized which is something that we expect since there is no `config.json` file created.