Remove scv/scvf.geometry()/corner()

Scv and Scvf do not need to store any corners and/or geometries. The geometry can be computed on-the-fly given an element geometry. We could provide such a feature in the element geometries.

Since I assume that this is a hardly used feature, and all occurrences in Dumux (can be counted on one hand) can use a replacement, I suggest to remove these interfaces without deprecation.

The benefit is much less memory usage when caching the scv/scvfs.

The proposed interface is two free functions

Geometry scvGeometry(fvElementGeometry, scv) Geometry scvfGeometry(fvElementGeometry, scvf)

Alternatively, we can think about

Geometry scvGeometry(element_geometry, scv) Geometry scvfGeometry(element_geometry, scvf)

then all local Dune index information has to be available from the scv/scvf object, while the first version allows to do some additional mapping only known to the fvElementGeometry implementation.