Add list of devices state properties

Similary to the list of availavle ‘actions’ (i.e. TurnOff, SetSpeed, SetDirection, ToggleLight, StartDimmer) - provide list of supported state properties, i.e. ‘light’, ‘power’, ‘speed’, ‘direction’

It’s usefull when creating devices in the integrations.

These are documented in the same place as the Actions, the Features section of the API docs.

I know. I mean it would be nice to get them via API in addition to list of ‘actions’