CI for ROS2 / Full ROS2 support

[Carter12s]

I'm pretty dang sure this library is ROS2 compatible / compliant because rosbridge looks basically identical, but I'd like to confirm that.

Build a 2nd CI docker image that has rosbridge (also checkout #41 and probably stick rosapi node in as well), and make a second github action to run CI for both ros1 and ros2.

While doing this, think about how maybe to support different versions of ros2 and what generating that CI docker image would look like for Rolling vs. other versions. Is there anyway to auto update the image / kick-off CI as rolling is updated? I think a problem we're going to run into here is finding the right base images to build off of? If there is a "good" ROS2_rolling:latest image we can use this might not be terrible, but we likely need to strip 95% of the contents out of that image.

Bonus: update the auto-badges in the readme to show CI status for ROS1 and ROS2 (or even better various ROS2 versions).

[Carter12s]

I made a major start on this and merged CI support for galactic.

However CI tests currently fail!

Main issue is in message generation. std_msgs/Header for ROS2 is different than ROS1's definition!

Will need more investigation. I think rolling / foxy support should be super easy and essentially copy paste of the galactic support. However, unclear how we will fix message generation for ros1 vs. ros2.