Separate GPU engines and make state follow official docs (part 1/2) (#2422)

* Use DeviceState for compute and i2m

* Migrate 2D class, more comments

* Migrate DMA copy engine

* Remove now unused code

* Replace GpuState by GpuAccessorState on GpuAcessor, since compute no longer has a GpuState

* More comments

* Add logging (disabled)

* Add back i2m on 3D engine

Ryujinx.Common/Memory/StructArrayHelpers.cs

@@ -640,5 +640,4 @@ namespace Ryujinx.Common.Memory
         public ref T this[int index] => ref ToSpan()[index];
         public Span<T> ToSpan() => MemoryMarshal.CreateSpan(ref _e0, 64);
     }
-
 }