Implement domain switch

[riker09]

We need to be able to add and switch between domains. A domain is specified by the user and can be one of light, temperature, volume. Pretty much anything that has a numeric range with a min and max value.

When switching domains (the default gesture for this when using the Nuimo with the official app is swiping left and right, if I remember correcly) the selected domain should be indicated in the LED matrix with a recognizable (yet customizable) icon (or text).

Where should the state (like selected domain) be stored? One possible solution is an input_select in Home Assistant.