Callback when a poll never returns

[BatmanAoD]

It seems like one possible use of pollcatch would be to detect polls that never return, and do some kind of recovery or alerting operation, such as emitting an alert event. Possibly there could be a separate Tokio task for detecting instances of before_poll_hook being called more than some configurable amount of time in the past, for which after_poll_hook has not yet been called.

Does that seem feasible?