Feat: EmitterMeshFaceShape - enhance particle emission uniformity

[capdevon]

This PR introduces significant improvements to the EmitterMeshFaceShape class. The core change involves updating the triangle point generation algorithm to use barycentric coordinates, ensuring a more uniform and accurate distribution of particles across mesh faces. The barycentric coordinate method is more standard and often easier to reason about for uniform distribution within a triangle.

Additionally, this PR includes:

• Improved Documentation: Detailed Javadoc comments have been added throughout the class, providing clearer explanations of its functionality, constructors, and methods for better code readability and maintainability.

Red Arrow: old algorithm (linear interpolation)
Green Arrow: barycentric coordinates