server/mssql: Handle stringifying large numbers

For geometry and geography values, the automatic json encoding on sql server would fail. So we need to convert it to a format the json encoding handles. Ideally we want this representation to be GeoJSON but sql server doesn't have any functions to convert to GeoJSON format. So we return it in WKT format

Start in the server/mssql handling for geometry and geography values and reproduce the automatic JSON-encoding failure described in the issue. Verify that the returned representation is WKT and that SQL Server responses no longer fail during JSON encoding.

Written by the indexing model from the issue text.