Problem 3094. Hankelize a matrix

Similar to Problem 42501. Toeplitize a matrix, let's consider Hankelization of a matrix.

Given an input matrix A, convert it to a Hankel matrix B by replacing each skew-diagonal of A with its mean. For example,

Input

   A = [3     7    10     2

        3     5     1     2

        6     3     2     7]

Output:

   B = [3     5     7     2 

        5     7     2     2

        7     2     2     7]