* This is the 3D counterpart to #49632
* Implemented a bit different as 3D works using instancing
After merged, both 2D and 3D classes will most likely be renamed in a separate PR to DisplayNotifier2D/3D.
* GIProbe is now VoxelGI
* BakedLightmap is now LightmapGI
As godot adds more ways to provide GI (as an example, SDFGI in 4.0), the different techniques (which have different pros/cons) need to be properly named to avoid confusion.
