Implement height watcher watchdog

[mkaczanowski]

TL;DR

We have noticed the case where height watcher "got stuck" as in, no height was reported for more than a day.

While the reason is unknown, it could be a bug in wss subscription or bad handling on blazar end... the mitigation would be to add the watchdog that can either restart the main loop, or "reset" the height watcher if there is no heights reported for XYZ blocks count.

Note that, when the upgrade is happening or pre check (halt height) the node can be down. In such case it is expected there is no new heights being reported.