Plane: move forward throttle output in VTOL modes to QuadPlane update

[IamPete1]

Finally getting to some of the tidy ups. This moves the outputting of forward throttle in VTOL modes up to QuadPlane output. There is no huge change in ordering, quadplane.update() is called a couple of lines above the set_throttle where were currently running this code.

ardupilot/ArduPlane/servos.cpp

Lines 871 to 883 in 6ce4dfe

	// do any transition updates for quadplane
	#if HAL_QUADPLANE_ENABLED
	quadplane.update();
	#endif
	if (flight_stage == AP_FixedWing::FlightStage::LAND) {
	// allow landing to override servos if it would like to
	landing.override_servos();
	}
	if (control_mode != &mode_manual) {
	set_throttle();
	}

[tridge]

delay till after 4.5.x is branched