blivet_package_list missing for Oracle Enterprise Linux

[ThiloSolbrig]

blivet_package_list won't be defined on Oracle Enterprise Linux (OEL) as there are no appropriate variable files in vars/directory. Since OEL, from this role's perspective, isn't more than a relabeled RHEL, it's sufficient to symlink every vars/RedHat_?.yml to the appropriate vars/OracleLinux_?.yml to add OEL support.

[plimptm]

Or the other way it could be handled is with a fallback vars/RedHat.yml file similar to the podman role.