feat(iot): Add shelly-ht-proimetheus exporter

The shelly H&T sensors are push bases sensors that turn off most of the
time. Therefore regular scraping is not possible, instead the sensors
push their status to a webhook. This deployment deploys such a webhook
which translates it to Prometheus, allowing for easy collection and
proper integration into the existing monitoring stack.

References:
https://github.com/LeSuisse/shelly-ht-action-prometheus