For UILists that doesn't use `filter_items()`, search filter doesn't work
along with invert button. For filter_items, invert case is already
handled in filter_items_by_name. In absense of that function,
handle the invert case inside `UI_list_filter_and_sort_items`. Existing logic
is a bit wrong. Now flags are adjusted, i.e. when search string matches, check
for invert status to decide whether items should be in the list or not.
Pull Request: https://projects.blender.org/blender/blender/pulls/139523
cf14be7644