Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph.
Each node in the graph contains a value (int) and a list of its neighbors.
Input: adjList = [[2,4],[1,3],[2,4],[1,3]]
Output: [[2,4],[1,3],[2,4],[1,3]]
[0, 100].1 <= Node.val <= 100Node.val is unique for each node.