Implement a voxelization algorithm which turns active constant tiles into leaf nodes if a given condition is met. This was originally desired due to constant tiles not being processed without an explicit densify call in some VDB operations (e.g. filtering). Some constant tiles may not need to be densified depending on their value and active neighbourhood, so an implementation that returns true/false based on a user defined functor would be ideal. For example, a pre VDB Blur style voxelisation should turn active tiles into leaf nodes if their neighbour values and active states differ up to the blur kernel width.