rate limit most parameter_update subscriptions

- parameter updates can be quite expensive because they trigger nearly all modules to reload all of their parameters immediately
 - limit modules from updating faster than once per second

src/modules/navigator/navigator.h

@@ -60,6 +60,7 @@
 #include <px4_platform_common/module_params.h>
 #include <uORB/Publication.hpp>
 #include <uORB/Subscription.hpp>
+#include <uORB/SubscriptionInterval.hpp>
 #include <uORB/topics/geofence_result.h>
 #include <uORB/topics/home_position.h>
 #include <uORB/topics/mission.h>
@@ -78,12 +79,13 @@
 #include <uORB/topics/vehicle_status.h>
 #include <uORB/uORB.h>
 
+using namespace time_literals;
+
 /**
  * Number of navigation modes that need on_active/on_inactive calls
  */
 #define NAVIGATOR_MODE_ARRAY_SIZE 9
 
-
 class Navigator : public ModuleBase<Navigator>, public ModuleParams
 {
 public:
@@ -332,11 +334,12 @@ private:
 	int		_local_pos_sub{-1};		/**< local position subscription */
 	int		_vehicle_status_sub{-1};	/**< local position subscription */
 
+	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
+
 	uORB::Subscription _global_pos_sub{ORB_ID(vehicle_global_position)};	/**< global position subscription */
 	uORB::Subscription _gps_pos_sub{ORB_ID(vehicle_gps_position)};		/**< gps position subscription */
 	uORB::Subscription _home_pos_sub{ORB_ID(home_position)};		/**< home position subscription */
 	uORB::Subscription _land_detected_sub{ORB_ID(vehicle_land_detected)};	/**< vehicle land detected subscription */
-	uORB::Subscription _parameter_update_sub{ORB_ID(parameter_update)};	/**< param update subscription */
 	uORB::Subscription _pos_ctrl_landing_status_sub{ORB_ID(position_controller_landing_status)};	/**< position controller landing status subscription */
 	uORB::Subscription _traffic_sub{ORB_ID(transponder_report)};		/**< traffic subscription */
 	uORB::Subscription _vehicle_command_sub{ORB_ID(vehicle_command)};	/**< vehicle commands (onboard and offboard) */