Please add a client notification to the agent termination event

[mykola-mokhnach-parloa]

Currently there is no way from the cli client code to know when the agent received SIGTERM or SIGINT and is in the graceful shutdown state. It would be useful to have a possibility for it to emit an event or provide a possibility to assign a callback, so one could execute a custom code when that happens.

Related to livekit/livekit-helm#116

[peter-assort]

+1 that would be nice!

FWIW you can do "cleanup" on the "job/worker" level using :

            # https://docs.livekit.io/agents/build/session/#post-processing-and-cleanup
            # Just add some logging when shutdown is initiated
            async def my_shutdown_hook() -> None:
                self._log_on_livekit_event_sync("shutdown callback")

            self.ctx.add_shutdown_callback(my_shutdown_hook)

If you feel real hacky, you can overwrite their SIGTERM catch in the JobEntry func,
but that can be dangerous you had been warned.