SNS_IK in ROS2

[chris-smith]

It's worth considering how we want to release SNS_IK into ROS2. AFAIA, we currently have few dependencies on ROS itself - excluding the build system I'm only aware of the logging (#38).

In ROS2 I believe the push is towards composable nodes and so what we distribute would likely be a ROS node itself that users could call through publishers, etc. I'm not sure we want to go "all in" on this model necessarily, which would imply we'd create a library similar to what we do today and then wrap it in a ROS2 node and distribute both. The biggest change we'd have to make to existing code would be replacing all the ROS_LOG macros and updating the build system.

@IanTheEngineer - any thoughts as a more seasoned ROS2 dev? Am I way off the mark?