Publish more robot's state (such as EM-Stop, Protective Stop, etc)

[urfeex]

Feature summary

Following up on ROS 1 issues regarding robot state diagnostics, we should publish more status information about the robot.

At the current state it might be good to hold still on that, as an API for that is implemented in ros-controls/ros2_control#2141.

Related issues

• diagnostics concept Universal_Robots_ROS_Driver#170
• Feature request : ROS diagnostics Universal_Robots_ROS_Driver#183
• https://github.com/ros-controls/roadmap/blob/master/design_drafts/hardware_status.md

Tasks

To complete this issue involves

• Implement the feature
• Make documentation
• Make Unit test
• Make example
• Test on real hardware