[WIP]: GPS clock set time updates

- remove drivers/gps set clock callback
 - drivers/gps try to set sensor_gps timestamp_sample as closely as possible
 - move mavlink timesync to new lib/timesync library
 - sensors/vehicle_gps_position consume all sensor_gps sources and determine time GPS utc time offset using lib/timesync
 - once time offset is stable update system clock if sufficiently different

msg/sensor_gps.msg

@@ -1,6 +1,7 @@
 # GPS position in WGS84 coordinates.
-# the field 'timestamp' is for the position & velocity (microseconds)
+# the field 'timestamp_sample' is for the position & velocity (microseconds)
 uint64 timestamp		# time since system start (microseconds)
+uint64 timestamp_sample
 
 uint32 device_id                # unique device ID for the sensor that does not change between power cycles
 
@@ -31,7 +32,6 @@ float32 vel_d_m_s		# GPS Down velocity, (metres/sec)
 float32 cog_rad			# Course over ground (NOT heading, but direction of movement), -PI..PI, (radians)
 bool vel_ned_valid		# True if NED velocity is valid
 
-int32 timestamp_time_relative	# timestamp + timestamp_time_relative = Time of the UTC timestamp since system start, (microseconds)
 uint64 time_utc_usec		# Timestamp (microseconds, UTC), this is the timestamp which comes from the gps module. It might be unavailable right after cold start, indicated by a value of 0
 
 uint8 satellites_used		# Number of satellites used

msg/templates/urtps/microRTPS_timesync.h.em

@@ -288,16 +288,16 @@ private:
 
 	/** Timesync Status msg Setters **/
 @[if version.parse(fastrtps_version) <= version.parse('1.7.2') or not ros2_distro]@
-	inline void setMsgSourceProtocol(timesync_status_msg_t *msg, const uint8_t &source_protocol) { msg->source_protocol_() = source_protocol; }
+	inline void setMsgSourceProtocol(timesync_status_msg_t *msg, const uint8_t &source_protocol) { msg->source_() = source_protocol; }
 	inline void setMsgRemoteTimeStamp(timesync_status_msg_t *msg, const uint64_t &remote_timestamp) { msg->remote_timestamp_() = remote_timestamp; }
 	inline void setMsgObservedOffset(timesync_status_msg_t *msg, const int64_t &observed_offset) { msg->observed_offset_() = observed_offset; }
 	inline void setMsgEstimatedOffset(timesync_status_msg_t *msg, const int64_t &estimated_offset) { msg->estimated_offset_() = estimated_offset; }
-	inline void setMsgRoundTripTime(timesync_status_msg_t *msg, const uint32_t &round_trip_time) { msg->round_trip_time_() = round_trip_time; }
+	//inline void setMsgRoundTripTime(timesync_status_msg_t *msg, const uint32_t &round_trip_time) { msg->round_trip_time_() = round_trip_time; }
 @[elif ros2_distro]@
-	inline void setMsgSourceProtocol(timesync_status_msg_t *msg, const uint8_t &source_protocol) { msg->source_protocol() = source_protocol; }
+	inline void setMsgSourceProtocol(timesync_status_msg_t *msg, const uint8_t &source_protocol) { msg->source() = source_protocol; }
 	inline void setMsgRemoteTimeStamp(timesync_status_msg_t *msg, const uint64_t &remote_timestamp) { msg->remote_timestamp() = remote_timestamp; }
 	inline void setMsgObservedOffset(timesync_status_msg_t *msg, const int64_t &observed_offset) { msg->observed_offset() = observed_offset; }
 	inline void setMsgEstimatedOffset(timesync_status_msg_t *msg, const int64_t &estimated_offset) { msg->estimated_offset() = estimated_offset; }
-	inline void setMsgRoundTripTime(timesync_status_msg_t *msg, const uint32_t &round_trip_time) { msg->round_trip_time() = round_trip_time; }
+	//inline void setMsgRoundTripTime(timesync_status_msg_t *msg, const uint32_t &round_trip_time) { msg->round_trip_time() = round_trip_time; }
 @[end if]@
 };

msg/timesync_status.msg

@@ -1,10 +1,17 @@
 uint64 timestamp			# time since system start (microseconds)
 
-uint8 SOURCE_PROTOCOL_MAVLINK = 0
-uint8 SOURCE_PROTOCOL_RTPS = 1
-uint8 source_protocol			# timesync source. Source can be MAVLink or the microRTPS bridge
+uint8 SOURCE_UNKNOWN          = 0
+uint8 SOURCE_PROTOCOL_MAVLINK = 1
+uint8 SOURCE_PROTOCOL_RTPS    = 2
+uint8 SOURCE_GPS1             = 3
+uint8 SOURCE_GPS2             = 4
+uint8 source                            # timesync source
 
-uint64 remote_timestamp			# remote system timestamp (microseconds)
 int64 observed_offset			# raw time offset directly observed from this timesync packet (microseconds)
 int64 estimated_offset			# smoothed time offset between companion system and PX4 (microseconds)
-uint32 round_trip_time			# round trip time of this timesync packet (microseconds)
+
+uint64 deviation
+
+int32 sequence
+
+bool converged

msg/vehicle_gps_position.msg

@@ -1,6 +1,7 @@
 # GPS position in WGS84 coordinates.
 # the field 'timestamp' is for the position & velocity (microseconds)
 uint64 timestamp		# time since system start (microseconds)
+uint64 timestamp_sample
 
 int32 lat			# Latitude in 1E-7 degrees
 int32 lon			# Longitude in 1E-7 degrees
@@ -17,6 +18,8 @@ float32 epv			# GPS vertical position accuracy (metres)
 float32 hdop			# Horizontal dilution of precision
 float32 vdop			# Vertical dilution of precision
 
+float32 pdop
+
 int32 noise_per_ms		# GPS noise per millisecond
 int32 jamming_indicator		# indicates jamming is occurring
 uint8 jamming_state		# indicates whether jamming has been detected or suspected by the receivers. O: Unknown, 1: OK, 2: Warning, 3: Critical
@@ -28,7 +31,6 @@ float32 vel_d_m_s		# GPS Down velocity, (metres/sec)
 float32 cog_rad			# Course over ground (NOT heading, but direction of movement), -PI..PI, (radians)
 bool vel_ned_valid		# True if NED velocity is valid
 
-int32 timestamp_time_relative	# timestamp + timestamp_time_relative = Time of the UTC timestamp since system start, (microseconds)
 uint64 time_utc_usec		# Timestamp (microseconds, UTC), this is the timestamp which comes from the gps module. It might be unavailable right after cold start, indicated by a value of 0
 
 uint8 satellites_used		# Number of satellites used