Blender Git Loki

Fix T69576, T74059: issues with rotation when adding objects

This clarifies logic in ED_object_add_generic_get_opts (see comments in
code).

Also following issues are adressed:
- do not enforce setting the op UI to WORLD when rotation is set (e.g.
on redo). This is not wrong (happens in world space), but is more
confusing than helpful (was added in own rB3b8a14a3c072).
- respect setting the User Preference to WORLD properly (could fail when
set to something else, then back to WORLD)

Maniphest Tasks: T69576

Differential Revision: https://developer.blender.org/D6943