Add cellToBoundary binding

[marklit]

This would be very useful. Exportings cells as geom fields into GPKG files would allow single SQL statements to produce files that open in QGIS for visualisation with no intermediate steps.

[isaacbrodsky]

@marklit (and anyone else who wants to chime in)

What format would you expect the output of cellToBoundary to be? List of coordinates? WKB? DuckDB's geometry type (not sure if this extension can produce that without making DuckDB Spatial a dependency)?

[marklit]

Maybe just a WKT polygon?

[marklit]

Fantastic, thank you very much!