Refactored audio conversion to reduce copying

More of the logic has been moved into SDL_AudioQueue,
allowing data to be converted directly from the input buffer.

include/SDL3/SDL_audio.h

@@ -789,13 +789,13 @@ extern DECLSPEC float SDLCALL SDL_GetAudioStreamFrequencyRatio(SDL_AudioStream *
 extern DECLSPEC int SDLCALL SDL_SetAudioStreamFrequencyRatio(SDL_AudioStream *stream, float ratio);
 
 /**
- * Add data to be converted/resampled to the stream.
+ * Add data to the stream.
  *
  * This data must match the format/channels/samplerate specified in the latest
  * call to SDL_SetAudioStreamFormat, or the format specified when creating the
  * stream if it hasn't been changed.
  *
- * Note that this call simply queues unconverted data for later. This is
+ * Note that this call simply copies the unconverted data for later. This is
  * different than SDL2, where data was converted during the Put call and the
  * Get call would just dequeue the previously-converted data.
  *