Preload command speedup, Texture/buffer data flush, blit shader fix (#30)

* Move encoder state to be tied to command buffer, so preload and background cbs have their own encoder state

* Texture buffer/data flush, blit shader fix

src/Ryujinx.Graphics.Metal/CommandBufferScoped.cs

@@ -9,12 +9,14 @@ namespace Ryujinx.Graphics.Metal
     {
         private readonly CommandBufferPool _pool;
         public MTLCommandBuffer CommandBuffer { get; }
+        public CommandBufferEncoder Encoders { get; }
         public int CommandBufferIndex { get; }
 
-        public CommandBufferScoped(CommandBufferPool pool, MTLCommandBuffer commandBuffer, int commandBufferIndex)
+        public CommandBufferScoped(CommandBufferPool pool, MTLCommandBuffer commandBuffer, CommandBufferEncoder encoders, int commandBufferIndex)
         {
             _pool = pool;
             CommandBuffer = commandBuffer;
+            Encoders = encoders;
             CommandBufferIndex = commandBufferIndex;
         }