Tesla: work in Autosteer mode

Primarily so we keep Autopark.

Problems (only tested with OP long):
- [ ] doesn't play any engage tone
- [ ] randomly shows cruise control unavailable when openpilot is in control
- [ ] says Autosteer is unavailable every engage with an error tone
- [ ] Autopilot ECU enforces wheel touch sporadically (comes and goes on its own)
- [ ] threw a red full screen immediate disengage when we canceled ACC via pressing brake
- [ ] Autosteer doesn't like it when openpilot steers, need to block Autosteer from enabling somehow
- [ ] FSD and Autosteer looks the same on CAN to us, but we don't want to support FSD as there's even more faults