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.
-- v9: user32: Remove NtUserDriverCallback* kernel callbacks. winex11.drv: Route kernel callbacks through user32. winemac.drv: Route kernel callbacks through user32. wineandroid.drv: Route kernel callbacks through user32. winevulkan: Route kernel callbacks through user32. user32: Add NtUserDispatchCallback kernel callback.