Refactor: optimize ShadowUtility and reduce object allocations

[capdevon]

Refactor: Optimize Shadow Utility & Enhance Javadoc

This PR introduces significant improvements to the ShadowUtil class, focusing on performance optimization, code refinement, and comprehensive Javadoc documentation.

Key changes include:

• Reduced Object Allocations: Minimized the creation of new Vector3f and other temporary objects, especially within performance-critical loops in methods like updateFrustumPoints and computeBoundForPoints, by leveraging TempVars. This aims to reduce garbage collection overhead and improve runtime performance.
• Refined OccludersExtractor: The OccludersExtractor inner class has been enhanced for better clarity and self-containment. Its constructor now explicitly handles all necessary state, making it more robust and easier to use.
• Comprehensive Javadoc: Added detailed Javadoc comments to all public methods, private helper methods, and the OccludersExtractor class. This improves code readability and maintainability for future development.
• Minor Code Clean-up: Removed commented-out code and applied minor formatting adjustments for better consistency.

These changes collectively make the ShadowUtil class more efficient, maintainable, and easier to understand for anyone working with shadow mapping in the engine, directly benefiting the performance of LightShadowRenderer and LightShadowFilter