add a periodic predicate health check

[rafaelcr]

For unknown reasons, sometimes the api falls out of sync with chainhook chain tip. This means the predicate gets cancelled or something else happens that makes the API not receive any blocks. To fix this, we should have a periodic health check on the API that (after a timer) checks the status of the predicate with chainhook, and if it comes unhealthy then it just re-registers it to go back to the chain tip.