Feature Suggestion Heli collective trim adjustment.

For Heli a collective trim adjustment would be really nice. Something that moves already leveled swash plates together at the same time.

So Motor1 Motor2 & Motor3 trim would be adjusted in sync according to their reversal. I think this is how most legacy flybarless controller configurators work, at least its how the ones I have used work. Its a lot more convenient and less prone to creating leveling issues. For heli adjusting each servo trim to move the collective trim up and down creates more opportunity for mistake and unlevealing the swash plate.

Im not sure viable this is in mission planner but it would make sense for it to just be another option under swashplate setup and have some up and down arrows you click on that adjust the trim params for the assigned motors.

This is not a parameter on its own though so im not sure how that would work.

This would be a really NICE TO HAVE feature.

Start at the swashplate setup entry point and trace how Motor1, Motor2, and Motor3 trim parameters and their reversals are handled. Confirm whether synchronized collective adjustment can use the existing parameters; done means an optional up/down control adjusts the assigned motor trims together without creating swashplate leveling issues.

Written by the indexing model from the issue text.