[akhila-pynam]

Description of Change

Refactors math/power_of_two.cpp to comply with repository contribution guidelines:

• Fixed the mathematical bug where 0 evaluated to a power of 2.
• Changed the return type from int (1/0) to idiomatic C++ bool (true/false).
• Removed the deprecated user_input_test() function containing interactive std::cin input.
• Added standard Doxygen docblocks (@brief, @param, @return).
• Added comprehensive self-tests with assert() covering 0, 1 ($2^0$), powers of 2, and non-powers of 2.

Fixes part of #2456

Checklist

• Added description of change
• Added tests and example, test must pass
• Added documentation so that the program is self-explanatory and educational - Doxygen guidelines
• 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.

Notes: Modernized math/power_of_two.cpp to adhere to contribution guidelines.