mgradm upgrade podman list doesn't should tags or error when not authenticated

[rjmateus]

When we run the command mgradm upgrade podman list without being authenticated we don't get any tags and it finishes with success.
We should try to provide some insides in case the registry needs authentication to return the tags.

[mbussolotto]

it should be an easy fix, this part of code should be added in list function

uyuni-tools/mgradm/shared/podman/podman.go

Lines 339 to 354 in 311105e

	inspectedHostValues, err := utils.InspectHost(false)
	if err != nil {
	return utils.Errorf(err, L("cannot inspect host values"))
	}
	pullArgs := []string{}
	_, scc_user_exist := inspectedHostValues["host_scc_username"]
	_, scc_user_password := inspectedHostValues["host_scc_password"]
	if scc_user_exist && scc_user_password && strings.Contains(serverImage, "registry.suse.com") {
	pullArgs = append(pullArgs, "--creds", inspectedHostValues["host_scc_username"]+":"+inspectedHostValues["host_scc_password"])
	}
	preparedImage, err := podman.PrepareImage(serverImage, image.PullPolicy, pullArgs...)
	if err != nil {
	return err
	}

[mbussolotto]

I'll verify it on top of #400, I think now just

authFile, cleaner, err := shared_podman.PodmanLogin()

would be enough