ROS Update Tool must Backup Calibrated URDF to exported_urdf directory

[hello-fazil]

Currently the command stretch_urdf_ros_update.py --ros2_rebuild only executes the commands to re-generate calibrated URDF but won't store it to exported_urdf directory in path ~/stretch_user/stretch-xx-yyyy/

[hello-binit]

https://github.com/hello-robot/stretch_body/blob/f329a9f7238ec2acf34b9a8ca7ede59af246439c/tools/bin/stretch_configure_tool.py#L316-L322