GPU: Track buffer migrations and flush source on incomplete copy (#3952)

* Track buffer migrations and flush source on incomplete copy

Makes sure that the modified range list is always from the latest iteration of the buffer, and flushes earlier iterations of a buffer if the data has not been migrated yet.

* Cleanup 1

* Reduce cost for redundant signal checks on Vulkan

* Only inherit the range list if there are pending ranges.

* Fix OpenGL

* Address Feedback

* Whoops

Ryujinx.Graphics.OpenGL/OpenGLRenderer.cs

@@ -238,6 +238,11 @@ namespace Ryujinx.Graphics.OpenGL
             _sync.Wait(id);
         }
 
+        public ulong GetCurrentSync()
+        {
+            return _sync.GetCurrent();
+        }
+
         public void Screenshot()
         {
             _window.ScreenCaptureRequested = true;