WASAPI: Raw stream mode

On Windows, the audio captured (through `build_input_stream`) seems to be passed through a default audio filter. I thought I had a bug in my code, because the sound recorded by `cpal` kept cutting out. This was particularly strange because sound from the same microphone in other apps that also didn't use exclusive mode (e.g. Discord) was fine. This issue did not happen on Linux. I found out that this issue was that Windows does audio processing by default. I did some further digging, and it seems that `cpal` does not use the `IAudioClient2::SetClientProperties`, which allows the `AUDCLNT_STREAMOPTIONS_RAW` flag to be set.