Faster construction of `PolygonArray` and `MultiPolygonArray` about spatialpandas

[ianthomas23]

I am not aware of a better approach to speed this up. Certainly creating spatialpandas geometry arrays includes some potentially slow copying of data and iterating over sequences, which could be better.

There is some hope for improvement on the horizon though. We have been looking into replacing some of the spatialpandas internal ragged arrays with awkward arrays, which will provide improvements in both speed and maintainability. This is proceeding relatively slowly though as it is not a high priority for any of the interested parties.