Add support for Voice selection, playback speed, and playback pitch

[edelabar]

Not sure if this is useful to anyone else, but something I needed, so it's yours if you want it. Thanks for this project in general, it's been a pleasure to use!

[m1guelpf]

Cherry-picked some basic improvements from here. Some questions on the rest of the PR:

• Would love to hear more about why you want a local ID for the Conversation
• Same for the responses stream
• In audioInterrumpted you mention "If you stop handling voice here you won't get the interrupt ended event.". Does that mean the audio gets interrupted but then never resumes?
• In the AudioInterruptHandlerDelegate, are there any specific reasons for using an OSAllocatedUnfairLock instead of an actor?

[eric-humane]

Cherry-picked some basic improvements from here. Some questions on the rest of the PR:

• Would love to hear more about why you want a local ID for the Conversation

prediction: offline storage and optimistic ui (prob could use like swift data and need stable id)

• Same for the responses stream

same as above, prob incase openai ever changes id formats (they have)

• In audioInterrumpted you mention "If you stop handling voice here you won't get the interrupt ended event.". Does that mean the audio gets interrupted but then never resumes?

prob this: https://developer.apple.com/documentation/avfaudio/handling-audio-interruptions

so you can:

1. Pause the player / suspend IO; do not call engine.stop().
2. Wait for the .ended case, then resume and, if necessary, reinstate the AVAudioSession category.

currently just tears everything down

• In the AudioInterruptHandlerDelegate, are there any specific reasons for using an OSAllocatedUnfairLock instead of an actor?

back pressure and latency. this is basically "free".

Apple Developer Documentation

Handling audio interruptions | Apple Developer Documentation

Observe audio session notifications to ensure that your app responds appropriately to interruptions.

[m1guelpf]

See #46 for a rewrite of this library to better accommodate WebRTC, which includes support for the speed API parameter.