Allowing for tariffs on meter

[arthurbenemann]

It would be quite nice to allow for tariffs to be setup as part of a meter, just as an extra configuration similar to "device_class".

Home assistant does not support setting tariff as part of the custumization.yaml, so they have to be added during creation of the utility_meter object. That is why placing the request here. The workaround at the moment is to create clone utility_meters, but that end-ups causing duplication on energy dashboard.

My use case is to split a water meter output based on the state of irrigation system.