Support Sql Geometry and Geography types

The default Newtonsoft serializer cannot serialize Sql Geometry and Geography types and we would need a custom convertor.
https://stackoverflow.com/questions/45848550/newtonsoft-json-jsonserializationexception-error-getting-value-from-value-on

The issue identifies SQL Geometry and Geography serialization and links a Newtonsoft.Json failure example, but names no files or tests. Start by reproducing the serialization failure in the extension’s SQL binding path; done means both types serialize successfully without the default serializer exception, with coverage for the behavior.

Written by the indexing model from the issue text.