Scatter Gather queries extensions

[sandjelkovic]

To use Scatter-Gather queries, gateway methods require ResponseType objects to be used to indicate return types.

To make it Kotlin idiomatic, extension methods on QueryGateway should be implemented to use reified generics, provide a method per ResponseType (Single without a suffix/Optional/Multiple Many) and forward those calls to existing methods on the QueryGateway.

New methods should also use Kotlin.time Duration in their signatures and convert to appropriate value and time unit for QueryGateway method invocation. Time unit of TimeUnit.MILLISECONDS might be a good option.
Since Kotlin time is still experimental, this might not be a good idea for the time being. When it stabilizes, it might be worth to reconsider

Examples of these types of extensions created for the query method can be found here.

This issue is similar to #11, but for different methods and types of queries.