Move all options to configuration groups with descriptive names

At the moment the documentation team hand assigns descriptive groups to each of our options. This is painful and error prone.

Instead, we should move all of our options to groups (with deprecated groups or default where it makes sense), and then make sure those groups have descriptions. The docs team can then hook off of that to generate their configuration documentation.

I think the first step is to add a hacking check to warn of options not in a group.