Artemis: Refactor and Optimize Methods in the Double Class

[mike-turintech]

This pull request introduces significant optimizations and refactoring to the methods in the Double class. Key changes include:

1. Optimized sumSquare Method: Reduced time complexity from O(n^2) to O(n) by eliminating nested loops and using a direct calculation for the sum of squares.
2. Refined sumTriangle Method: Improved efficiency by adjusting the loop range and simplifying the summation logic for triangular numbers.
3. Rewritten countPairs Method: Enhanced performance from O(n^2) to O(n) by using a HashMap to count occurrences, simplifying the logic.
4. Simplified countDuplicates Method: Increased readability and efficiency by removing inner loops and adding boundary checks.

Overall, these changes improve the performance and clarity of the Double class methods while preserving their original functionality.