feature: add check for frozen node

[dylanschultzie]

This could potentially be done by:

1. scan /status and check if latest block height is too far away
2. check if there are current peers?

[dylanschultzie]

Upon further inspection, it appears 1 is already being done.

I'm guessing, then, that the issue is that because events are no longer being consumed by the websocket, it can't know that the machine has stalled. Perhaps that means a secondary loop that checks cc.lastBlockTime against cc.lastBlockTime.Before(time.Now().Add(time.Duration(-cc.Alerts.Stalled)*time.Minute), but not in its current location?

[dylanschultzie]

seems like that's what's happening here... https://github.com/blockpane/tenderduty/blob/main/td2/rpc.go#L120