refactor(useNodesData): improve selector equality function (#3976)

* improved selector equality function for useNodesData

* fixed selector & useNodesData example

* added shallow-node-data as system function

packages/system/src/utils/shallow-node-data.ts

@@ -0,0 +1,20 @@
+import { NodeBase } from '../types';
+
+type NodeData = Pick<NodeBase, 'id' | 'type' | 'data'>;
+
+export function shallowNodeData(a: NodeData | NodeData[], b: NodeData | NodeData[]) {
+  const _a = Array.isArray(a) ? a : [a];
+  const _b = Array.isArray(b) ? b : [b];
+
+  if (_a.length !== _b.length) {
+    return false;
+  }
+
+  for (let i = 0; i < _a.length; i++) {
+    if (_a[i].id !== _b[i].id || _a[i].type !== _b[i].type || !Object.is(_a[i].data, _b[i].data)) {
+      return false;
+    }
+  }
+
+  return true;
+}