feat: add neon number implementation

[Nithwin]

Description of Change

Added a C++ implementation of the Neon Number algorithm in the math directory.
The implementation includes checking if a number is a "Neon Number" (where the sum of digits of its square equals the number itself).

Key features:

• Implemented is_neon function in math namespace.
• Added full Doxygen documentation.
• Included self-tests using cassert to verify functionality (tested with 0, 1, 9, 12, 45).

Checklist

• Added description of change
• Added file name matches File name guidelines
• Added tests and example, test must pass
• Added documentation so that the program is self-explanatory and educational
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• Search previous suggestions before making a new one, as yours may be a duplicate.
• I acknowledge that all my contributions will be made under the project's license.

[Nithwin]

Why my PR was not being merged and why no one is replying to this atleast

[github-actions]

This pull request has been automatically marked as abandoned because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[github-actions]

Please ping one of the maintainers once you commit the changes requested or make improvements on the code. If this is not the case and you need some help, feel free to ask for help in our Gitter channel or our Discord server. Thank you for your contributions!