A new PointDataPartitioner that is built on top of the PointPartitioner and a rewrite of VDB point moving to use this new API. This will also extend it to be able to support merging of different VDB points grids and will significantly improve performance and memory usage.

There are a number of other prerequisite tasks that I'll include under this ticket, but scope to remain core library only, Houdini-related functionality will follow in a subsequent ticket.