Audren: Implement polyphase upsampler (#4256)

* Audren: Implement polyphase upsampler

* prefer shifting to modulo

* prefer MathF

* fix nits

* rm ResampleForUpsampler

* oop

* Array20

* nits

Ryujinx.Audio/Renderer/Server/Upsampler/UpsamplerState.cs

@@ -37,6 +37,11 @@ namespace Ryujinx.Audio.Renderer.Server.Upsampler
         /// </summary>
         public ushort[] InputBufferIndices;
 
+        /// <summary>
+        /// State of each input buffer index kept across invocations of the upsampler.
+        /// </summary>
+        public UpsamplerBufferState[] BufferStates;
+
         /// <summary>
         /// Create a new <see cref="UpsamplerState"/>.
         /// </summary>