Overwatch 2 verifies that every kernel callback that is run, lives in user32. Introduce a callback in user32 that just forwards to the other modules' callbacks.
-- v11: user32: Remove NtUserDriverCallback* kernel callbacks. winex11.drv: Route kernel callbacks through user32. winex11.drv: Pass a struct to x11drv_ime_set_result. winex11.drv: Pass a struct to x11drv_dnd_post_drop. winemac.drv: Route kernel callbacks through user32.