sndcpy-auto cast shell

This is an forked copy of https://github.com/rom1v/sndcpy to include following:

• Casting auto audio cast authorization in mobile with audio mute and shell input using sndcpy-auto shell script
• Device Selection if multiple devices are connected taken from https://gist.github.com/dtmilano/4537110

The purpose is to enable audio forwarding while mirroring with scrcpy. However, it can be used independently.