Add an explicit `ordering`

[MoritzStefaner]

Build order is implicit in feature order, so anything that re-sorts loses it. Our pipeline re-sorts
in several places.

Ask: an explicit dense ordering column

[mszell]

Thx! @Manuel-Knepper I hope it's OK if I assign you, since you are already working on lbn currently.
If you have any questions, let Moritz know here.