refactor(geoarrow-pyarrow): Use python type_id and geobuffers implementation

[paleolimbot]

This PR removes three pieces of usage of geoarrow-c that will let geoarrow-c narrow its implementation down to what it's good at, which is conversions. The key pieces are:

• The geobuffers implementation now uses pyarrow. Also some bugs were fixed!
• The as_geoarrow kernel parameterized its "to" type with an integer, which was the last remaining usage of the CVectorType (which was rewritten in Python a while ago in geoarrow-types).
• A stray enum usage which was the last remianing usage of the non-python enums