Add Sudoku-Solver and Tower of Hanoi

[Shrasht]

Tower of Hanoi Solution:

Recursively solves the Tower of Hanoi problem.
Moves all disks from the source rod to the destination rod using the auxiliary rod, following the rules of the problem.

Sudoku Solver:

Solves any valid 9x9 Sudoku puzzle using backtracking.
Efficiently fills in empty cells while checking constraints for row, column, and subgrid consistency.