fixed-wing attitude control: add option to disable manual yaw

[sfuhrer]

Solved Problem

• yaw stick still maps directly to actuator_controls[YAW] (seems to have been an oversight in 8372a78)
• not possible to disable manual yawing if not desired

Solution

• remove direct stick-->controls, only change body_rates_setpoint(2) which is then fed into the controller. Note: body_rates_setpoint(2) is previously calculated by the attitude controller for turn coordination.
• introduce FW_YR_MAX_ADD param and use instead of FW_Y_RMAX to set the effect of the stick to the rate setpoint. If no effect is desired, it can be set to 0.

Alternatives

We could also completely disable it in any attitude controlled mode?

Test coverage

SITL tested.

[dagar]

We could also completely disable it in any attitude controlled mode?

Do we know anyone that actually wants it?

Otherwise if keeping it, for manual attitude mode (aka stabilized) we have parameters FW_MAN_R_MAX and FW_MAN_P_MAX, so perhaps something like FW_MAN_YR... would be appropriate here.

[sfuhrer]

Do we know anyone that actually wants it?

E.g. for FW landings where you want to align with the runway at the end of the flight. Or on gliders to increase the amount of drag through slipping to land at a steeper angle.

Otherwise if keeping it, for manual attitude mode (aka stabilized) we have parameters FW_MAN_R_MAX and FW_MAN_P_MAX, so perhaps something like FW_MAN_YR... would be appropriate here.

Alright, pushed it as FW_MAN_YR_MAX now.