feat(reactflowUtils.ts): add getMiddlePoint function to calculate the average position of multiple nodes

The getMiddlePoint function calculates the average position of multiple nodes by summing up the x and y coordinates of each node and dividing them by the total number of nodes. This allows us to find the middle point or center of a group of nodes. This function can be used to determine the position of a new node based on the average position of existing nodes.

src/frontend/src/utils/reactflowUtils.ts

@@ -385,3 +385,19 @@ export function customStringify(obj: any): string {
   );
   return `{${keyValuePairs.join(",")}}`;
 }
+
+export function getMiddlePoint(nodes: Node[]) {
+  let middlePointX = 0;
+  let middlePointY = 0;
+
+  nodes.forEach((node) => {
+    middlePointX += node.position.x;
+    middlePointY += node.position.y;
+  });
+
+  const totalNodes = nodes.length;
+  const averageX = middlePointX / totalNodes;
+  const averageY = middlePointY / totalNodes;
+
+  return { x: averageX, y: averageY };
+}