GEOGRAPHY handling

In https://github.com/paleolimbot/duckdb-geography/pull/31 it came up that we can no longer get geoarrow.wkb auto converted from Arrow because an arrow extension can only be registered once (and "geography" in GeoArrow land is also geoarrow.wkb with `"edges": "spherical"` or one of the other esoteric values that were added because of Parquet but may never be used). I'm not sure how to solve this now that geoarrow.wkb registration lives in DuckDB...will anybody over there let GEOGRAPHY live in DuckDB proper?

Also a note that I've rewritten s2geography to use views on WKB or anything similar to it ( https://github.com/paleolimbot/s2geography/pull/82 and following PRs) and am working over the next month or so to speed up the most common functions. At some point I will try to port that into duckdb-geography as well 🙂

Start with duckdb-geography PR #31 and the issue's discussion of geoarrow.wkb registration and Arrow conversion. Determine whether GEOGRAPHY should live in DuckDB proper, then define a decision that resolves the one-registration constraint and the relationship to the rewritten s2geography approach.

Written by the indexing model from the issue text.