Set night/dark mode

[grischard]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like

The Home Assistant app should expose a switch for dark/night mode.

Additional context

Especially once #1333 gets resolved, it would be very nice to be able to use Home Assistant to set dark/night mode. Computers without an ambient light sensor (Mac Pro?) would also be able to use external illumination sensors that way.

It can apparently be done through AppleScript.

[grischard]

Like a few other issues, this depends on a mechanism to expose switches in the mobile_app integration, and should be tagged as blocked: core.

I couldn't find a ticket or feature request for that, so I've created one.