Audio: Add more settings

[wheremyfoodat]

Adds some audio-related settings to both the regular frontends and the libretro core

• A volume slider that lets the user control the emulator volume, as well as letting them amplify audio (Using a logarithmic volume scale and a hard clipper). This allows users to control the audio volume from within the app (Which is particularly important on MacOS due to Mac not having an OS volume mixer) as well as letting them boost the game audio above normal volume.
• A mute audio setting
• A setting to control whether AAC audio is enabled, for debugging & researching which games use AAC and for which tracks.