Fix uss class for resize top-let hadle in resize handle

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Manipulators/ResizeSideHandle.cs

                 }
                 case ResizeHandleAnchor.TopLeft:
                 {
-                    AddToClassList("vertical");
+                    AddToClassList("diagonal");
                     AddToClassList("top-left");
                     break;
                 }