reorganization to support SSR for component library in docusaurus

platform/ui/src/components/ViewportPane/ViewportPane.jsx

@@ -6,7 +6,7 @@ import { useDrop } from 'react-dnd';
 // NOTE: If we found a way to make `useDrop` conditional,
 // Or we provided a HOC of this component, we could provide
 // this UI without the DragAndDropContext dependency.
-function ViewportPane({
+export function ViewportPane({
   children,
   className,
   isActive,