Initial support for GPU channels (#2372)

* Ground work for separate GPU channels

* Rename TextureManager to TextureCache

* Decouple texture bindings management from the texture cache

* Rename BufferManager to BufferCache

* Decouple buffer bindings management from the buffer cache

* More comments and proper disposal

* PR feedback

* Force host state update on channel switch

* Typo

* PR feedback

* Missing using

Ryujinx.Graphics.Gpu/Image/TexturePool.cs

@@ -57,7 +57,7 @@ namespace Ryujinx.Graphics.Gpu.Image
 
                 ProcessDereferenceQueue();
 
-                texture = Context.Methods.TextureManager.FindOrCreateTexture(TextureSearchFlags.ForSampler, info, layerSize);
+                texture = Context.Methods.TextureCache.FindOrCreateTexture(TextureSearchFlags.ForSampler, info, layerSize);
 
                 // If this happens, then the texture address is invalid, we can't add it to the cache.
                 if (texture == null)