token/generate case sensitivity for clientLibrary

[dk1844]

Background

New feature of case-sensitivity-driven groups filtering has been added to the backend in #146
This feature should also be present in the client library API

Feature

Add an option to explicitly add case-sensitivity flag to the token/generate call in the client library API

Business Value

Clients using the client library should be able to get the pre-v2 behavior that is actually available on the backend