Properly handle global state changes like network interface becoming unavailable

[pavel-kirienko]

This is perhaps related to https://github.com/OpenCyphal/pycyphal/issues/224

When the network interface becomes unavailable (e.g., CAN adapter disconnected, IP address changed, Cyphal/serial TCP connection closed), all services dependent on the active transport instance should be notified such that the state change can be adequately processed.