Haydn: Part 1 (#2007)

* Haydn: Part 1

Based on my reverse of audio 11.0.0.

As always, core implementation under LGPLv3 for the same reasons as for Amadeus.

This place the bases of a more flexible audio system while making audout & audin accurate.

This have the following improvements:
- Complete reimplementation of audout and audin.
- Audin currently only have a dummy backend.
- Dramatically reduce CPU usage by up to 50% in common cases (SoundIO and OpenAL).
- Audio Renderer now can output to 5.1 devices when supported.
- Audio Renderer init its backend on demand instead of keeping two up all the time.
- All backends implementation are now in their own project.
- Ryujinx.Audio.Renderer was renamed Ryujinx.Audio and was refactored because of this.

As a note, games having issues with OpenAL haven't improved and will not
because of OpenAL design (stopping when buffers finish playing causing
possible audio "pops" when buffers are very small).

* Update for latest hexkyz's edits on Switchbrew

* audren: Rollback channel configuration changes

* Address gdkchan's comments

* Fix typo in OpenAL backend driver

* Address last comments

* Fix a nit

* Address gdkchan's comments

Ryujinx.HLE/HOS/Services/Audio/AudioIn/IAudioIn.cs

@@ -0,0 +1,34 @@
+using Ryujinx.Audio.Common;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Audio.AudioIn
+{
+    interface IAudioIn : IDisposable
+    {
+        AudioDeviceState GetState();
+
+        ResultCode Start();
+
+        ResultCode Stop();
+
+        ResultCode AppendBuffer(ulong bufferTag, ref AudioUserBuffer buffer);
+
+        // NOTE: This is broken by design... not quite sure what it's used for (if anything in production).
+        ResultCode AppendUacBuffer(ulong bufferTag, ref AudioUserBuffer buffer, uint handle);
+
+        KEvent RegisterBufferEvent();
+
+        ResultCode GetReleasedBuffers(Span<ulong> releasedBuffers, out uint releasedCount);
+
+        bool ContainsBuffer(ulong bufferTag);
+
+        uint GetBufferCount();
+
+        bool FlushBuffers();
+
+        void SetVolume(float volume);
+
+        float GetVolume();
+    }
+}