Support a non-generic query

[jsgoupil]

Most cases, I will need to have either a Point or a Polygon when querying. In both cases, I end up with a IGeometry.

JsonConvert.DeserializeObject does support passing the type at runtime. Forcing to have the type at compile time makes it quite complex for a simple fetch.

It would be interesting to have something like:

var layer = await secureGateway.DescribeLayer(endpoint);
secureGateway.Query(queryOptions, layer.GeometryType);