Support GEOMETRY types + Add spatial index

[morgo]

We would like to be able to support geometry types with open street map data, for example:

ALTER TABLE osm_points_of_interest
    ADD COLUMN points_of_interest GEOMETRY GENERATED ALWAYS AS (ST_GeomFromText(geometry_wkt, 4326, 'axis-order=long-lat')) STORED NOT NULL SRID 4326,
    ADD SPATIAL INDEX idx_points_of_interest (points_of_interest);

Currently this fails in parsing:

• The GEOMETRY types are not parseable, see Improve error message on SPATIAL types/indexes not supported pingcap/tidb#29370 (there is a PR open on this!)
• CREATE TABLE with a SPATIAL INDEX or ALTER TABLE .. ADD SPATIAL INDEX is not currently supported by this PR (but CREATE SPATIAL INDEX works)