For keystone, we have new functionality called domain scoped roles, which will mean that roles now have a domain argument upon create/ update/ delete/ list/show

However we already have a domain argument because we use it to scope user/group/project.

We should, in preparation for 3.0.0, switch to using `role assignment list` for the `role list --domain` operations. This was previously a v3 specific operation, but we can munge v2 to include it as well.