FW Pos C: add option to disable airspeed setpoint via stick input

-rename FW_POSCTL_INV_ST to FW_POS_STK_CONF and make bitmask out of it:
  - bit 0: alternative mapping (height rate on throttle stick, airspeed on pitch)
  - bit 1: enable/disable airspeed setpoints via stick

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/fw_pos_control_l1/FixedwingPositionControl.hpp

@@ -286,6 +286,11 @@ private:
 	param_t _param_handle_airspeed_trans{PARAM_INVALID};
 	float _param_airspeed_trans{NAN};
 
+	enum StickConfig {
+		STICK_CONFIG_SWAP_STICKS_BIT = (1 << 0),
+		STICK_CONFIG_ENABLE_AIRSPEED_SP_MANUAL_BIT = (1 << 1)
+	};
+
 	// Update our local parameter cache.
 	int		parameters_update();
 
@@ -461,7 +466,7 @@ private:
 		(ParamFloat<px4::params::FW_THR_MIN>) _param_fw_thr_min,
 		(ParamFloat<px4::params::FW_THR_SLEW_MAX>) _param_fw_thr_slew_max,
 
-		(ParamBool<px4::params::FW_POSCTL_INV_ST>) _param_fw_posctl_inv_st,
+		(ParamInt<px4::params::FW_POS_STK_CONF>) _param_fw_pos_stk_conf,
 
 		(ParamInt<px4::params::FW_GPSF_LT>) _param_nav_gpsf_lt,
 		(ParamFloat<px4::params::FW_GPSF_R>) _param_nav_gpsf_r,