RTC-15321 - Use setDisplayMediaRequestHandler instead

[axeleriksson147]

https://perzoinc.atlassian.net/browse/RTC-15321

https://www.electronjs.org/docs/latest/api/desktop-capturer - In their documentation they're implementing screen sharing with setDisplayMediaRequestHandler. Electron the injects itself into the native navigator.mediaDevices.getDisplayMedia and returns whatever we set in the callback. Trying this solution instead of sending commands from the client and then processing them and returning the stream. This is because we've had issues with getting the sources and the screen picker showing up.

Guesses what could've made our SDA screensharing more unstable:

• The desktopCapturer.getSources API is now only available in the main process. This has been changed in order to improve the default security of Electron apps.