Add py versions of nodes from logging_demo pkg

Presently there are some CPP based nodes in the logging_demo pkg while py versions do not exist.
Also, we recently added newer logging service related nodes in demo_nodes_cpp and demo_nodes_py. We could consider deprecating the logging_demo pkg and move the CPP nodes from there into demo_nodes_cpp. At the same time port py versions of these nodes into demo_nodes_py. 