Detect when we're logged-in to the ghcr and display an error to the user

Currently, if a user is logged-in to the ghcr in the terminal, the `podman pull` commands will fail. We might be able to detect this and give the information to the user that running `podman logout ghcr.io` could solve this issue.

We probably want to link to documentation online about this, rather than including the answer directly in the application.