Plane: auto-deploy landing gear on fixed wing landing

[tridge]

if LGR_OPTIONS is set to auto-deploy then deploy
this affects all fixed wing auto-landings

[Hwurzburg]

metadata in LGR_OPTIONS needs a tweak

[IamPete1]

We have this case in servos.cpp, seems a bit odd to be checking in another place too.

ardupilot/ArduPlane/servos.cpp

Lines 754 to 769 in ab59a00

	void Plane::set_landing_gear(void)
	{
	if (control_mode == &mode_auto && arming.is_armed_and_safety_off() && is_flying() && gear.last_flight_stage != flight_stage) {
	switch (flight_stage) {
	case AP_FixedWing::FlightStage::LAND:
	g2.landing_gear.deploy_for_landing();
	break;
	case AP_FixedWing::FlightStage::NORMAL:
	g2.landing_gear.retract_after_takeoff();
	break;
	default:
	break;
	}
	}
	gear.last_flight_stage = flight_stage;
	}

Maybe just move the control_mode == &mode_auto check down into the retract case so they deploy in any mode but only retract in auto.