Move critical nodes into ComposableNodeContainer

[macmacal]

If there will be any problem with performance hiccups or bottlenecks, we should move as much of ros2_control and MoveIt2 nodes into a ComposableNodeContainer.

An example can be found here:
https://github.com/moveit/moveit2/blob/53979331bcaa472ddd3a3fc895907172df01374d/moveit_ros/moveit_servo/launch/servo_example.launch.py#L93