HdSt : Rendering functionality for HdStorm

HdSt is responsible for the core rendering functionality of the HdStorm Hydra renderer.

Overview

HdSt can pull data from Hydra's renderIndex (potentially data coming from multiple scenegraph inputs) and it can create one or more command buffers that aggregate and share the underlying GPU resources, such as primvar data. It is optimized for both dynamically changing scenes and cached playback.