Implement the next phases of bounds improvement design #96968.
Mainly the following changes:
Don't use `Object.runtime.bb` for performance caching volume bounds.
This is redundant with the cache in most geometry data-block types.
Instead, this becomes `Object.runtime.bounds_eval`, and is only used
where it's actually needed: syncing the bounds from the evaluated
geometry in the active depsgraph to the original object.
Remove all redundant functions to access geometry bounds with an
Object argument. These make the whole design confusing, since they
access geometry bounds at an object level.
Use `std::optional<Bounds<float3>>` to pass and store bounds instead
of an allocated `BoundBox` struct. This uses less space, avoids
small heap allocations, and generally simplifies code, since we
usually only want the min and max anyway.
After this, to avoid performance regressions, we should also cache
bounds in volumes, and maybe the legacy curve and GP data types
(though it might not be worth the effort for those legacy types).
Pull Request: https://projects.blender.org/blender/blender/pulls/114933