Move some settlement mods to late-loading group

[sibir-ine]

Ref

May need to be placed later than Scrap Everything, so we should consider adding a new group for settlement mods with precombines.

Link to example mod, other mods in the series are linked on its page & should be considered as well. One of them was added in #558.

[MacSplody]

It's going to be hard to group settlement mods.
Mainly because their position can be somewhat dynamic, depending on the mods being used.
Maybe if we have conditional grouping.
But the issue is, we would end up having to add a lot of groups.
As a single group for all settlement mods is going to be too much of a problem.

Horizon and Frost are to be placed after most other mods.
PRP ideally should be after most other mods, but there are several versions.
So their position might be different depending on the version of PRP being used.
And if Settlement mods need to be after all PRP versions or just some, then their position may vary.

There's also the problem of actually grouping all settlement mods together.
What order do we set them in, if there are no conflicts?
If we don't set an order, then we'll have to group all patches for those mods as well.
Or as I mentioned earlier, we'd have to add a group for each settlement mod.
Which could be fine, if we were certain that fixed position would work when using either PRP, Frost or Horizon.