GM Camera ACC: cancel camera cruise when OP long

Camera sends alerts over GMLAN which we can't control, so you'll get messages like "hill too steep" and other strange alerts that don't affect anything that are caused by mismatches between the camera thinking it's engaged (it doesn't check the ECM status :facepalm:) when the ECM actually isn't (like if OP prevents a fault from the brake pressure issue at a stop).

Send a cancel button to the camera if it is enabled with OP long to silence some of these alerts

TODO:
- [ ] Check this doesn't break anything
- [ ] Check it actually works