Add the mine counts to a completed Minesweeper board.
Minesweeper is a popular game where the user has to find the mines using numeric hints that indicate how many mines are directly adjacent (horizontally, vertically, diagonally) to a square.
In this exercise you have to create some code that counts the number of mines adjacent to a given empty square and replaces that square with the count.
The board is a rectangle composed of blank space (' ') characters.
A mine is represented by an asterisk (*) character.
If a given space has no adjacent mines at all, leave that square blank.
For example you may receive a 5 x 4 board like this (empty spaces are represented here with the '·' character for display on screen):
·*·*·
··*··
··*··
·····
And your code will transform it into this:
1*3*1
13*31
·2*2·
·111·
Reference: https://exercism.org/tracks/rust/exercises/minesweeper