Support .contains_properly by expanding pairwise_point_in_polygon to support multipolygon input?

[isVoid]

#910 adopts quadtree_point_in_polygon to support python's .contains_properly API. However, quadtree_PiP is in nature all-pairs. There is a complex translation step involved to convert this result to match geopandas output. On the other hand, libcuspatial do support pairwise operation in C++, the missing link is that this API only supports "single polygon array" input. Perhaps we can explore expanding this API to accept multipolygon input and simplify .contains_properly implementation?

[harrism]

I also would like to explore combining both C++ all-pairs PIP algorithms into a single function that automatically chooses the optimal path (perhaps with an optional quadtree argument to pass in a pre-built index for reuse) and always returns the results in a format that is optimal for the Python UI.

[harrism]

I think this should be an issue. I've already decided that this is important to do. :)