Artemis: Refactor and Optimize Mathematical Functions in Double Class

[mike-turintech]

This pull request introduces optimizations and refactoring to the mathematical functions in the Double class, enhancing performance and clarity. Key changes include:

1. Optimized sumSquare Method: Reduced time complexity from O(n^2) to O(n) by eliminating nested loops.
2. Refined sumTriangle Method: Simplified triangular number calculation and improved efficiency by removing inner loops.
3. Revised countPairs Method: Replaced nested loops with a HashMap for counting duplicates, improving performance from O(n^2) to O(n).
4. Simplified countDuplicates Method: Enhanced readability by using a single loop to check for index equality.

These changes improve the performance and maintainability of the code, aligning with best practices for algorithm design.