Add switch to disable camera (Snapshot and Live) about hkcam

[brutella]

For privacy reasons it would be nice to have a switch to disable the camera. The camera should then provide no image or maybe simply a black one. The switch then could also be automated with "I leave home"/"I arrive at home".

That's a great idea.

In the current version there is some kind of switch present, however its functionality is not clear to me. What's the purpose of this switch?

The switch has no functionality at the moment.

[brutella]

Since iOS 13, Apple's Home app seem to enforce the value of the power switch.
If the switch is off, streaming is disabled in the Home app.
Snapshots still show up.