[mqtt][homeassistant] Set channel type to Number for some sensor components

[bodiroga]

Hi guys!

Right now, the homeassistant binding defines all sensor components as String items (TextValue as defined by MQTT generic binding). As far as I know, we can not change it directly to NumberValue, because some sensor components can have discrete values, but we could use the "unit_of_measurement" variable to determine the magnitude of the reported information. Having a look at the mqtt messages sent by the sensor, I can see that the "value_template" information could also be used for this (value_json.temperature, value_json.humidity, value_json.battery, value_json.linkquality...).

What do you think?

Thanks for your work and best regards,

Aitor

[bodiroga]

Thanks @jochen314 for implementing it! Closed by #6763.