refactor(gameplay): remove dead code and simplify chunk neighbor context

Remove the large commented-out `init_chunks()` function, and eliminate the `affected_neighbor` tracking in `gen_chunks_internal()`. This simplifies the neighbor context building and removes unused vertex data regeneration for affected neighbors.

include/Cubed/gameplay/world.hpp

@@ -96,10 +96,7 @@ private:
                                          const ChunkPosSet&);
     void
     build_neighbor_context_for_new_chunks(ConstChunkMap& new_chunks_neighbor,
-                                          ChunkPtrUpdateList& affected_neighbor,
                                           const ChunkPairVector& new_chunks);
-    void build_neighbor_context_for_affected_neighbors(ChunkPtrUpdateList&,
-                                                       ConstChunkMap&);
 
 public:
     World();