Role selection template done.

[=JpS=SgtRock]

I defined it as a standalone mission to make it easy to test. It should make it easier to include it in other missions, too.

If you're interested in checking it out, I spent a few hours documenting how it works and how it's put together in these Wiki pages.  The GitLab page for the mission itself is here.  Or you can just grab the whole thing as a zipfile.