feat: support geospatial results on the kernel path

[cathleeny]

Summary

• add the kernel-only, default-enabled enable_geospatial_support connection option
• return canonical {"srid": int, "wkb": bytes} values when enabled and WKT / EWKT strings when disabled
• preserve logical GEOMETRY / GEOGRAPHY Arrow metadata
• pass the value through the typed PyO3 argument only; it is never forwarded to SEA

Dependency

Depends on databricks/databricks-sql-kernel#361 at b7e9310b27be16a6c42490e58c4b5c4a525320bc.

Validation

• unit suite: 1,023 passed, 4 skipped, 2 deselected
• real-kernel signature/routing tests against the exact kernel extension: 2 passed
• live Reyden E2E against the exact extension: default-enabled, explicit-enabled, and disabled-string modes passed through both direct Arrow-scalar and pandas row conversion paths, including Arrow metadata, WKB equality, and nulls