Added Bit Manipulation Problems in C++

[ShivaKrishna-07]

This pull request includes implementations of various bit manipulation problems in C++. The following files have been added:

• counting-bits.cpp: A solution to count the number of 1 bits for each number from 0 to n.
• divide-two-integers.cpp: A custom implementation of integer division without using multiplication or division operators.
• single-number-I.cpp: A solution to find the single number in an array where every other number appears twice.
• single-number-II.cpp: A solution to find the single number in an array where every number appears three times except for one.
• single-number-III.cpp: A solution to find two single numbers in an array where every other number appears twice.
• subsets.cpp: A solution to generate all possible subsets of a given set of numbers.

Each solution includes appropriate handling of edge cases and is designed to follow best practices in C++ programming.

[pravocodes]

Put this folder in cpp folder.