VoiceProcessingIO sample project

As discussed in WWDC 2022 Lab ID VP9N6MT8SX with Apple Engineer Julian Y from Core Audio.

Primary issue:

• kAudioUnitSubType_VoiceProcessingIO does not lead to "Mic Mode" getting enabled (see scenario 1) with built-in input/output

I've tried to shorten the code as much as possible, but CoreAudio requires a reasonable amount of boilerplate - Audio.swift should contain relevant code to the question, with some of that boilerplate separated out into files like Devices, Formats, Types, etc.

Instructions:

1. Scenario 1:

• Build and run the sample project with no headphones connected
• Select default mac input and output. Verify that sample rates are correct
• Click "Setup"
• Click "Start"

Expected results at this point: - Sample app will play through input to output with kAudioUnitSubType_VoiceProcessingIO enabled (currently working) - "Mic Mode" control in Control Center should be enabled (Not currently happening on Monterey 12.3.1 on MacBook Pro M1)

2. Scenario 2:

• Switch to AirPods (for both input and output)
• Make sure that the sample rates are correct (24,000)
• Click "Setup"
• Click "Start"

Expected results at this point: - Sample app will play through input to output with kAudioUnitSubType_VoiceProcessingIO enabled (currently working) - "Mic Mode" control in Control Center should be enabled (Not currently happening on Monterey 12.3.1 on MacBook Pro M1)