The original motivation for this was to prepare the API to support having more
than one tree log for each zone. Currently, there is always a well defined tree
log for each zone (when the inspection index is taken into account). However,
for closures that is less true and there may be more than one equaly valid tree
log. While we might still want to show only one value per socket initially, it
would probably be nice in the future to support accessing information from
multiple evaluations at the same time (also for loops).
None of this is implemented here though, it's just a refactor with no expected
functional changes.
Pull Request: https://projects.blender.org/blender/blender/pulls/137166