Given a binary tree `root` and an integer `target`, delete all the leaf nodes with value `target`.

Note that once you delete a leaf node with value `target`, if its parent node becomes a leaf node and has the value `target`, it should also be deleted (you need to continue doing that until you cannot).

Example 1:

    Input: root = [1,2,3,2,null,2,4], target = 2
    Output: [1,null,3,null,4]
    Explanation: Leaf nodes in green with value (target = 2) are removed (Picture in left).
    After removing, new nodes become leaf nodes with value (target = 2) (Picture in center).

Example 2:

    Input: root = [1,3,3,3,2], target = 3
    Output: [1,3,null,null,2]

Example 3:

    Input: root = [1,2,null,2,null,2], target = 2
    Output: [1]
    Explanation: Leaf nodes in green with value (target = 2) are removed at each step.

Constraints:

- The number of nodes in the tree is in the range `[1, 3000]`.
- `1 <= Node.val, target <= 1000`