Backfill building's kind_detail from spatial intersection with POI

[nvkelso]

Similar to the area callout in #348 and the landuse_kind in #1226 and a logical extension of the id based kind_detail assingment in #487 and this comment #487 (comment)...

Many buildings have a single POI on top of them that has information about the type of business. We can do a spatial intersection of the POIs and buildings ... when there is single match we can take the POI's kind and backfill it into the building's kind_detail... when there are multiple we can either see if they are all the same and assign that, or assign a synthetic "multiuse" value.

We'd need to consider impact on building merging at mid-zooms either by stripping off the kind_detail &/or simplifying values like we do on landuse pre-merge.

This would support more building color coding in the map styles.