OpenArm ROS 2 0.9.1

OpenArm ROS 2 0.9.0

Cleanup the package structure (#30)

- We are keeping the bimanual and single arm descriptions in one
standalone package
[openarm_description](https://github.com/enactic/openarm_description)
- Similarly, bringup scripts for both single arm and bimanual setups
will be unified.
- mujoco related hardware code will be maintained in
[openarm_mujoco](https://github.com/enactic/openarm_mujoco).