Add an option to only record the audio from the game

[wyndon]

OBS has an option called "Capture audio" under the Game Capture settings, which automatically adds an audio source in OBS for the recorded game. This is very useful as it allows to only record the game audio, and not the audio of the whole desktop, by enabling this feature + muting the desktop audio.

I think this should be the default behavior.

[CrookedJ]

It would be great if it would record game audio and discord audio to separate tracks