fix(custom-grid): use City2TABULA's use type for 3D buildings #263

A 3D building in a custom grid with no OSM outline gets f_class=yes and is treated as residential (for example DEBY_LOD2_7672144, about 5,500 m²). City2TABULA now serves a use type per building (THD-Spatial-AI/city2tabula#210; for the Netherlands from BAG in THD-Spatial-AI/city2tabula#217, for Germany from the ALKIS function code). Map that use type to pylovo's building classes and to the BuEM building type instead of the OSM class. No code table in EnerPlanET.

The configurator header and the area-limit warning are done in #274.