Add ABB IRB4600 robot descriptions

[dpiet]

This integrates the original abb_irb4600_support package from the ROS-I abb_experimental repo and updates for ROS2. Tested with simulated and real IRB4600_60_205 robot.

[AndyZe]

It's also good to hear that you were able to run this on hardware. I guess that means the README's weren't awful. :+1:

[dpiet]

Thanks @AndyZe and co. for putting together this package update for ROS2!