This patch cleanup and refactors the render pipeline compositor render
code to deduplicate code and clarify usage.
The unused this_scene arguemenet was removed, per-node functions were
introduced to simplify loops, C++ Set was used instead of GSet, and
scene change is now detected by any rendered scene in the set.
Pull Request: https://projects.blender.org/blender/blender/pulls/124028
29451489ae