Use official entity state formatting functions when available.

[HA 2023.9 introduced new functions](https://developers.home-assistant.io/blog/2023/08/29/hass-format-state/) to enable custom cards to format entity state and entity attributes values. This PR uses these new functions (if supported) unless the user specified a custom format option. More here: https://developers.home-assistant.io/docs/frontend/data#entity-state-formatting Should close #333, close #308, close #286 and maybe #220