Energy: Add fixed daily cost

[DevBre]

Possible interesting

Dynamic Energy Cost

There is still no Individual devices cost functionality in Energy Dashboard which has a feature request here: Energy: Cost for the individual devices So there is workaround using Gas part of the Energy Dashboard, but if you have gas as well, there is no good way how to do it. If you have fixed electricity price, its pretty easy to with an template sensor, but if you have changing electricity price like Nordpool for example, it gets pretty complex. I had a method how to do it from a device pow…