Create MergeSort.cpp

[Omji-Kesharwani]

Description:

Implement the Merge Sort algorithm to sort an array of integers in ascending order. The algorithm uses a divide-and-conquer approach, recursively breaking the array into two halves, sorting them, and then merging the sorted halves to form a fully sorted array.

Fixes #issue_number_here

Type of change: Added a mergesort file in searching folder.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Change in documentation

Checklist:

• [ ] My code follows the style guidelines of this project.
• [ ] I have performed a self-review of my own code.
• [ ] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have made corresponding changes to the documentation.
• [ ] My changes generate no new warnings.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] New and existing unit tests pass locally with my changes.
• [ ] Any dependent changes have been merged and published in downstream modules.
• [ ] Necessary documentation changes done
• [ ] I have added the file in the correct directory

Screenshots / Video: