Depends on !3970
This MR greatly simplifies wlr_cursor, which at the moment does multiple things at once:
- applies (device-specific) coordinate transformations → this functionality is moved out to a helper
- acts as a proxy for pointer-like devices → removed
- can be reintroduced as another helper, but that doesn't seem very useful
- this is the reason why some input events still have the device pointer in them
- manages
wlr_output_cursorobjects (this includes setting surfaces/images) → the only thingwlr_cursordoes now