vehicles: add new vehicle type: Airship (#14862)

Co-authored-by: Anton Erasmus <anton@flycloudline.com>
Co-authored-by: Beat Küng <beat-kueng@gmx.net>

ROMFS/px4fmu_common/init.d/rc.airship_apps

@@ -0,0 +1,59 @@
+#!/bin/sh
+#
+# Standard apps for airships. Attitude/Position estimator, Attitude/Position control.
+#
+# NOTE: Script variables are declared/initialized/unset in the rcS script.
+#
+
+###############################################################################
+#                       Begin Estimator Group Selection                       #
+###############################################################################
+
+#
+# LPE
+#
+if param compare SYS_MC_EST_GROUP 1
+then
+	#
+	# Try to start LPE. If it fails, start EKF2 as a default.
+	# Unfortunately we do not build it on px4_fmu-v2 due to a limited flash.
+	#
+	if attitude_estimator_q start
+	then
+		echo "WARN [init] Estimator LPE unsupported, EKF2 recommended."
+		local_position_estimator start
+	else
+		echo "ERROR [init] Estimator LPE not available. Using EKF2"
+		param set SYS_MC_EST_GROUP 2
+		param save
+		reboot
+	fi
+else
+	#
+	# Q estimator (attitude estimation only)
+	#
+	if param compare SYS_MC_EST_GROUP 3
+	then
+		attitude_estimator_q start
+	else
+		#
+		# EKF2
+		#
+		param set SYS_MC_EST_GROUP 2
+		ekf2 start
+	fi
+fi
+
+###############################################################################
+#                        End Estimator Group Selection                        #
+###############################################################################
+
+#
+# Start Airship Attitude Controller.
+#
+airship_att_control start
+
+#
+# Start Land Detector.
+#
+land_detector start airship