Feature Request: Provide rain information via MQTT

[Vrumfondel]

Since I found the online-weather information of current rain status very unreliable, I would like to provide the information if it is currently raining - and trigger the delay from this - via MQTT (I got a rain sensor in my home automation).

Would be nice if this can be added as an option to online or wired sensor.

[rayshobby]

The features added by this PR (#340) should support this, but we are currently still reviewing the PR and trying to iron out all potential issues.

[Vrumfondel]

In the change description for this PR I only see the ability to OUTPUT the weatherdata via MQTT, but not INPUT it.
Do I miss something there?

[rayshobby]

I believe Stefan's firmware (PR #340) can read weather data from MQTT as well. I will double check.

[rayshobby]

Per Stefan's instructions:
https://opensprinklershop.de/2023/01/29/analog-sensor-konfiguration-aktivieren/?v=85d1a9c488d7
it supports a type of sensor called MQTT sensor. I don't know all the details but I believe this can be used to define a MQTT rain sensor.