Add lifecycle subscriber example and test#646

Open

carmiac wants to merge 3 commits intoros2:rollingfrom

carmiac:milner/lifecycle_demo

Commits on Jul 31, 2023

Lifecycle subscription testing
Adam Milner
committed
Passing tests. Need to add lifecycle_node_listener tests
Adam Milner
committed

Commits on Aug 1, 2023

Working tests for lifecycle subscriber node.
Adam Milner
committed