Turn ControllerManager into a LifecycleNode

[bmagyar]

Is your feature request related to a problem? Please describe.

Over the years there were many ways to detect if the controller_manager was available for loading/starting controllers. ROS2 offers a much nicer way of doing this which also helps with launch dependencies at the launch file level for free -> LifecycleNodes.

Describe the solution you'd like

Implement a LifecycleNode interface for ControllerManager