firewall: Live event updates

Be able to get live updates from events via the web API, maybe using websockets. Things to be done are more or less:

[x] Setup a specialized channel in firewall that emits messages to a UDS, this must be done along with rustqlite inserts and logging.
[x] Setup websockets to listen for informatio
[x] Add /firewall/listen
[x] Do any special handling, if needed, to prevent the firewall::Manager to get all sockets occupied serving live envents.
- Maybe create a new socket per events suscriber?
- Listen events from a task/thread?

AOx0 / adam