feat(map_loader): update loading path for multiple pcd files

Signed-off-by: kminoda <[email protected]>

autoware_launch/launch/autoware.launch.xml

@@ -28,7 +28,7 @@
   <arg name="check_external_emergency_heartbeat" default="false"/>
   <!-- Map -->
   <arg name="lanelet2_map_file" default="lanelet2_map.osm" description="lanelet2 map file name"/>
-  <arg name="pointcloud_map_file" default="pointcloud_map.pcd" description="pointcloud map file name"/>
+  <arg name="pointcloud_map_file" default="pointcloud_map" description="pointcloud map file name ({FILE}.pcd file will be searched first, pcd files under {FILE} directory will be searched next)"/>
   <!-- System -->
   <arg name="system_run_mode" default="online" description="run mode in system"/>
   <arg name="launch_system_monitor" default="true" description="launch system monitor"/>