GpuBuffer obsoletes ComputeBuffer to prevent confusion that it's compute exclusive
* Non templated version because sometimes your buffer will have various types
* Usage flags can be combined now, e.g a buffer can be used as an IndexBuffer but also ByteAddress for compute shader
* Added additional error checking, exposed readonly properties for count/size/usage
* Added CodeUpgrader for ComputeBuffer -> GpuBuffer
* Fix Terrain materials buffer overflowing its gpu buffer