Refactor Visject surface nodes cache to reuse between graphs

Source/Editor/Editor.cs

@@ -724,8 +724,8 @@ namespace FlaxEditor
 
             // Cleanup
             Undo.Dispose();
-            Surface.VisualScriptSurface.NodesCache.Clear();
-            Surface.AnimGraphSurface.NodesCache.Clear();
+            foreach (var cache in Surface.VisjectSurface.NodesCache.Caches.ToArray())
+                cache.Clear();
             Instance = null;
 
             // Invoke new instance if need to open a project