Introduce draft SCS-compatible IaaS "next" (#985)

At present, it's functionally equivalent to v5.1, but it uses more fine-grained testcases.

* Use codename for draft version to better distinguish from stable
* Show drafts only in table_full, details_full
* Resort scope versions so drafts go after non-drafts

Signed-off-by: Matthias Büchse <matthias.buechse@alasca.cloud>

Author: mbuechse