[FEAT] Send notification if collector stops sending data

I have scrutiny set up with binary collectors on various hosts connected via wireguard, and the web app and influx db running on docker. It would be great if scrutiny kept track of how much time has passed since the last upload from a collector, and send a notification if that exceeds the average of say the last 4 upload intervals plus some threshold.

Currently, if a collector goes down, I'd never know it, and I could potentially miss a drive issue because the data just isn't getting reported.

Workaround for the time being is to add a healthchecks or uptime-kuma ping via curl in the cron job itself. It would be nice to not need that overhead, though!