Add option to show on lock screen

**Is your feature request related to a problem? Please describe.**
Building a dashboard with home assistant app requires the screen to always stay on - or have some clever way to turn the (tablet) screen on and off.

**Describe the solution you'd like**
I'd like to have an option to show home assistant app on the lock screen. This enables the app to turn the display physically on and off.
This on the other hand can be used to trigger on/off based on a (motion) sensor state.

**Describe alternatives you've considered, if any**
BrowserMod allows to turn the screen black, but this keeps the backlight running (when not on an oled display, which my tablet does not have.)

**Additional context**
-