Export non-primitive Shapes to URDF

[ygoumaz]

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As reported in https://github.com/cyberbotics/webots_ros2/pull/770#issuecomment-1629127839, currently <visual> tags of exported URDFs are written from BoundingObjects. Mesh export is currently not supported. While it is not recommend to use meshes as BoundingObjects for performance reasons, it still leads to cases where parts of the robot have no visual tag at all.

<collision> geometries should be exported from BoundingObjects while <visual> geometries should be exported from Shapes/Cadshapes and support Meshes.