Improve and organize Binary Search implementations in C++

[namitaa15]

Description

• Added two proper C++ implementations of Binary Search:
  • Iterative approach: Input and search logic separated into main and function.
  • Recursive approach: Input and search logic separated into main and function.
• Improved code structure for readability and clarity.
• Both versions take array size and elements as input from the user.

Reason

• Makes it easier for beginners to understand both iterative and recursive binary search methods.
• Follows best coding practices by separating logic (functions) and user input (main).
• Code is clean, easy to read, and ready for further improvement or extension.