This commit fixes a bug that would cause the frontend API function
obs_frontend_set_current_scene_collection to never be successful. Due
to the bug, the following null pointer check would always fail, so the
action would never be triggered.
Modification by Jim: Instead of fixing the typo that caused this to
occur, make it so both scene collection menus and profile menus both use
"file_name" consistently.
Closesjp9000/obs-studio#712