More "get state" controls for smart devices

[iandouglas]

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

I'd like to monitor when the camera is turned on/off on my nest doorbell, or to toggle the state of the microphone and maybe send some prerecorded audio messages if a delivery comes by, etc.

Describe the solution you'd like

Maybe these would be traits we could get as part of fetching a device. If it has a camera, let us know if the camera is on/off, if the device has a mic, is that on/off, etc. If the microphone to talk to a person is muted, let us unmute and send a small audio sample to the speaker, etc.

Describe alternatives you've considered

I've looked through the SDK and existing public code and don't see any way to check if the camera/mic are on or off. I tried a CaptureImage control thinking it would fail if the camera was off, or take a blank picture, but that seemed a bit extreme and also couldn't get it working.

Additional context

n/a