Added XACRO to dependencies, corrected demo launch file (space-ros#46)

Author: namikxgithub

custom_gz_plugins/dependencies_source_pkgs.repos

@@ -124,3 +124,7 @@ repositories:
     type: git
     url: https://github.com/ros2/yaml_cpp_vendor.git
     version: humble
+  xacro:
+    type: git
+    url: https://github.com/ros/xacro.git
+    version: ros2

custom_gz_plugins/launch/demo_world.launch.py

@@ -22,7 +22,9 @@ def generate_launch_description():
            ':'.join([environ.get('GZ_SIM_SYSTEM_PLUGIN_PATH', default=''),
                      environ.get('LD_LIBRARY_PATH', default='')]),
            'GZ_SIM_RESOURCE_PATH':
-           ':'.join([mars_rover_demos_path, mars_rover_models_path + '/models'])}
+           ':'.join([mars_rover_demos_path, 
+                     mars_rover_models_path + '/models',
+                     mars_rover_demos_path + '/worlds'])}
 
     urdf_model_path = os.path.join(mars_rover_models_path, 'models', 'curiosity_path',
         'urdf', 'curiosity_mars_rover.xacro.urdf')
@@ -77,6 +79,10 @@ def generate_launch_description():
         arguments=[
             '-name', 'curiosity_path',
             '-topic', robot_description,
+            "-z", "4",
+            "-x", "0",
+            "-y", "0",
+            "-Y", "0",
         ],
         output='screen'
     )