This reduces visible banding in indirect lighting and reflections.
Sharp reflections now match more closely the original scene.
The downside of this change is that clipping may appear in reflections
in extremely bright scenes, but this should not be a concern in most
scenes.
* 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.
