Add support for USB audio interfaces on iPadOS

In the past, external audio interfaces weren't exposed at the system level on iPadOS; resulting in this request to add custom functionality to select connected audio interfaces. Technically this previous request has already been fulfilled, You can select your input device via iPadOS itself. But for whatever reason, some audio devices vanish from Apple's AirPlay menu as soon as you join a call in specifically Discord.

I have a Rodecaster Pro II connected to my iPad via the USB 2 connection, I can use this connection as an input & output system-wide. Furthermore, other video/audio conferencing applications don't trip out when I connect to a call. For example, when connected to any call type in Microsoft Teams the Rodecaster is still visible/select-able, and works great.