load_mon: rename low_stack -> task_stack_info & always publish it

- use uorb queue to not drop any info, only do 2 tasks per cycle
- also print a warning on low stack (which will be added to ulog)

this allows to gather statistics of each task's stack usage over time.

msg/CMakeLists.txt

@@ -42,6 +42,7 @@ set(msg_file_names
 	battery_status.msg
 	camera_trigger.msg
 	commander_state.msg
+	collision_report.msg
 	control_state.msg
 	cpuload.msg
 	debug_key_value.msg
@@ -73,6 +74,7 @@ set(msg_file_names
 	mc_virtual_rates_setpoint.msg
 	mission.msg
 	mission_result.msg
+	mount_orientation.msg
 	multirotor_motor_limits.msg
 	offboard_control_mode.msg
 	optical_flow.msg
@@ -96,6 +98,7 @@ set(msg_file_names
 	servorail_status.msg
 	subsystem_info.msg
 	system_power.msg
+	task_stack_info.msg
 	tecs_status.msg
 	telemetry_status.msg
 	test_motor.msg
@@ -118,14 +121,11 @@ set(msg_file_names
 	vehicle_local_position.msg
 	vehicle_local_position_setpoint.msg
 	vehicle_rates_setpoint.msg
+	vehicle_roi.msg
 	vehicle_status.msg
 	vision_position_estimate.msg
 	vtol_vehicle_status.msg
 	wind_estimate.msg
-	vehicle_roi.msg
-	mount_orientation.msg
-	collision_report.msg
-	low_stack.msg
 	)
 
 # Get absolute paths

msg/task_stack_info.msg

@@ -1,3 +1,5 @@
+# stack information for a single running process
+
 uint8 MAX_REPORT_TASK_NAME_LEN = 16
 
 uint16 stack_free