Unify Device state retrieval

[farmio]

We should unify the way states are retrieved from Devices. Now some use functions (Sensor.resolve_state()) and some properties (Switch.state).
Devices with multiple RemoteValues have multiple properties (brightness, color, etc. )
I'd suggest we implement a property for all devices that returns all (known/used/used+unused) states as dict so it's easier to write callback functions for multiple types of Device().

[github-actions]

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