refactor(zoomPanHelper): export and simplify

src/index.ts

@@ -9,6 +9,7 @@ export { getSmoothStepPath } from './components/Edges/SmoothStepEdge';
 export { getMarkerEnd, getCenter as getEdgeCenter } from './components/Edges/utils';
 
 export { isNode, isEdge, removeElements, addEdge, getOutgoers, getIncomers, getConnectedEdges } from './utils/graph';
+export { default as useZoomPanHelper } from './hooks/useZoomPanHelper';
 
 export * from './additional-components';
 export * from './store/hooks';