Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree.

  Example 1:

Input: root = [4,2,6,1,3] Output: 1

Example 2:

Input: root = [1,0,48,null,null,12,49] Output: 1

  Constraints:

The number of nodes in the tree is in the range [2, 10⁴].
0 <= Node.val <= 10⁵

  Note: This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/