Create 12_ChangeBitOfNumber.cs

12. We are given integer number n, value v (v=0 or 1) and a position p. Write a sequence of operators that modifies n to hold the value v at the position p from the binary representation of n.
     Example: n = 5 (00000101), p=3, v=1 -> 13 (00001101)
              n = 5 (00000101), p=2, v=0 -> 1 (00000001)