Add underground parking to landuse, pois layers

[nvkelso]

• What did you see? zilch
• What did you expect to see? An underground parking POI
• What map location are you having problems with? https://www.openstreetmap.org/way/162924135#map=19/51.52465/-0.03168

We do now correctly classify building kind_detail values for various parking=* values thanks to #1423. But for underground parking that's not a building we should still show a landuse polygon for that and a PONI poi.

[nvkelso]

Oddly this one works, so?

• https://www.openstreetmap.org/way/59847115#map=19/51.51887/-0.12278