car.capnp: LongitudinalPIDTuning kd derivative term

[ntegan1]

Allow for cars that utilize the derivative term in longitudinal PID tuning
to log the derivative term along with the rest.

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[ntegan1]

Trying to think of how to log Toyota longitudinal tuning.

cereal/log.capnp ControlsState-> {upAccelCmd, uiAccelCmd, ufAccelCmd} no longer help with longitudinal tuning as only the default tune of 1.0 kf term is used, and custom carcontroller pid turns the model's desired accel into pcm accel command.

We aren't logging this car-specific tune.

Could we add logging to CarParams for a secondary kp, kd, ki, kf as well as logging for secondary ui, up, uf, ud accel Cmd?