Update availability detector

Inspired by the Low battery level detection automation, I tried to replace my countless individual update checks with one single check to rule them all.

Github Gist: Home Assistant Blueprint: Update availability detector for all entities · GitHub

The idea is simple: check every Update entity in HA, keep the ones with updates not on the exceptions list, and return the final list as a string.

Open your Home Assistant instance and show the blueprint import dialog with a specific blueprint pre-filled.

This is my first blueprint, so looking forward to feedback.