geofence: added pre-arm check if too close to fence

- prevents dangerous situations during and after takeoff when the geofence
breach avoidance tries to push the vehicle away from the fence

Signed-off-by: RomanBapst <bapstroman@gmail.com>

msg/geofence_result.msg

@@ -7,6 +7,7 @@ uint8 GF_ACTION_TERMINATE = 4               # flight termination
 uint8 GF_ACTION_LAND = 5		    # switch to AUTO|LAND
 
 bool geofence_violated		# true if the geofence is violated
+bool geofence_too_close_on_ground	# true if vehicle close than GF_MINDIST_GND while landed or disarmed
 uint8 geofence_action       	# action to take when geofence is violated
 
 bool home_required		# true if the geofence requires a valid home position

msg/vehicle_status.msg

@@ -88,6 +88,7 @@ bool high_latency_data_link_lost 			# Set to true if the high latency data link
 bool engine_failure				# Set to true if an engine failure is detected
 bool mission_failure				# Set to true if mission could not continue/finish
 bool geofence_violated
+bool geofence_too_close_on_ground               # the vehicle is too close to a geofence boundary while being on the ground
 
 uint8 failure_detector_status			# Bitmask containing FailureDetector status [0, 0, 0, 0, 0, FAILURE_ALT, FAILURE_PITCH, FAILURE_ROLL]