Perform Compressed<->Uncompressed copies using Pixel Buffer Objects (#1732)

* PBO single layer copy, part 1

Still needs ability to take and set width/height slices. (using pack paramaters)

* PBO Copies pt 2

* Some fixes and cleanup.

* Misc Cleanup

* Move handle into the TextureInfo interface.

This interface is shared between texture storages and views.

* Move unscaled copy to the TextureCopy class.

* Address feedback.

Ryujinx.Graphics.OpenGL/Image/TextureStorage.cs

@@ -5,7 +5,7 @@ using System;
 
 namespace Ryujinx.Graphics.OpenGL.Image
 {
-    class TextureStorage
+    class TextureStorage : ITextureInfo 
     {
         public int Handle { get; private set; }
         public float ScaleFactor { get; private set; }