Extending the techniques of T4544/T4554, generate schema definition files for all native configsession functions currently implemented, and reduce to a single directive/resolver to handle this collection of requests. This simplifies the current infrastructure going forward and allows one to easily add any remaining configsession functions. In addition, we will remove the original, templated, 'high-level' API config requests, and set up automatic generation of schema definitions for that collection in a separate task.