geom/m49232: octree node geometry quantisation
This introduces a quantization scheme into the octree coding process, enables adaptive geometry quantization for different regions of the point cloud. This in-loop scheme is independent of the any quantisation performed in non-normative pre-processing at the input to the encoder. At a particular depth of the octree, the remaining (uncoded) position bits of each point are quantised according to a per-node (or rather, per-subtree) QP. The QP itself is signalled as an offset to a base QP. The following configuration parameters are added: positionQuantisationEnabled positionBaseQp positionQuantisationOctreeDepth