refactor: Enhance QuadraticRadical with Factory Pattern
- Introduced QuadraticRadicalFactory to streamline the creation of QuadraticRadical instances.
- Updated QuadraticRadical class to use references for the parameter
d_and adjusted constructors accordingly. - Refactored unit tests to utilize the factory for creating QuadraticRadical objects, improving test clarity and maintainability.
- Added new test cases to validate factory functionality and ensure correct behavior of QuadraticRadical operations.