This converts the public `uiItemFullO` function to an object oriented
API (an `uiLayout::op` overload), matching recents changes in the API.
Changes includes the removal of the paramether `IDProperty *properties`
that seems unused (all places just sets `nullptr`, can be added as last
argument with `nullptr` as default value though), and instead of using a
return paramether the function now returns the pointer to write properties.
Pull Request: https://projects.blender.org/blender/blender/pulls/138961
44160a0524