Refactor: PointLightShadowRenderer reduce object allocations

[capdevon]

This PR refactors the PointLightShadowRenderer class to improve readability and maintainability. Key changes include:

• Replaces repeated inline vector negations (e.g., Vector3f.UNIT_X.mult(-1f)) with clearly named constants (X_NEG, Y_NEG, Z_NEG).
• Updates camera axis assignments in updateShadowCams() to use these new constants, reducing code duplication and potential errors.
• Minor improvements to JavaDoc for clarity and consistency.

These changes make the codebase cleaner and easier to understand without altering any functionality.

[richardTingle]

(Apart from the author change) looks good. Makes sense to avoid pointless negative vector allocations

[capdevon]

Hi guys,
Could you tell me why there is an error in the Screenshot Test? I just restored the original name of the class author after a previous change that passed the test.

[riccardobl]

Hi guys, Could you tell me why there is an error in the Screenshot Test? I just restored the original name of the class author after a previous change that passed the test.

looks like a timeout, sometime github action is a bit flaky, i've rerunned it