Implemented Code to string-manipulation

[Coderx85]

Title: Implemented Substring, Subsequence, and Palindrome Checks in C++

Description:

This pull request addresses the following issues:

• Issue #X: Substring of a String
• Issue #Y: Subsequence of a String
• Issue #Z: Palindrome String

Changes Made:

• Added a C++ file StringOperations.cpp to the repository.
• Implemented functions to check if a string contains a substring, if it contains a subsequence, and if it is a palindrome.

Additional Information:

• isSubstring checks if a string contains a specified substring.
• isSubsequence determines if a string contains a specified subsequence.
• isPalindrome verifies if a string is a palindrome.

All functions have been tested and produce correct results.

I'm open to feedback and ready to make any necessary adjustments. Thank you for considering this contribution!