Decouple ROFL event notifier and sub-handler

[peternose]

The ROFL event notifier should be decoupled from the ROFL sub-handler to ensure that these structures are independent of each other. Additionally, the ROFL event notifier should terminate when the ROFL component is stopped (e.g., during an upgrade) to prevent resource leaks.

Ideally, every RONL component should have a handler and a notifier, and every ROFL component should have a sub-handler and a sub-notifier.