gz_bridge: project local position instead of using navsat global pos

The issue is that the global position produced by gz is inconsistent
with the velocity, leading to navigation issues when moving away from
the origin.

src/modules/simulation/gz_bridge/GZBridge.cpp

@@ -721,9 +721,10 @@ void GZBridge::navSatCallback(const gz::msgs::NavSat &msg)
 		return;
 	}
 
-	double latitude = msg.latitude_deg();
-	double longitude = msg.longitude_deg();
-	double altitude = msg.altitude();
+	double latitude;
+	double longitude;
+	_pos_ref.reproject(_position_prev(0), _position_prev(1), latitude, longitude);
+	double altitude = _alt_ref + (-_position_prev(2));
 	float vel_north = msg.velocity_north();
 	float vel_east = msg.velocity_east();
 	float vel_down = -msg.velocity_up();