[CHESSBOARD_MOVE] Generate moves

[DatUser]

For this task, the assignee(s) has(ve) to implement the generate_legal_moves function of chessboard class that will generate the moves for every token. And also make a function that checks if a move is correct is_legal_move.

Please, let everyone know about your progress.

[DogodaDozo]

Add of a function appending all elements of one array into another one. Then I get all the moves of the different pieces on the board, and add them to a final array of moves.