Add lifecycle timers

[carmiac]

This adds lifecycle timers which start when the node activates and cancel when the node deactivates. There is a demo available at https://github.com/carmiac/demos/blob/lifecycle_timer/lifecycle/src/lifecycle_timer.cpp

[ros-discourse]

This pull request has been mentioned on ROS Discourse. There might be relevant details there:

https://discourse.ros.org/t/lifecycle-node-improvements/32706/1