Ellipsoid primitive

[JasmineLowen]

Objective

• Implement the Ellipsoid primitive listed in Tracking Issue: Primitive Shapes #10572
• also some credit on Tracking Issue: Primitive Shapes #10572 (comment) for talking about working on this but being to shy to submit a PR

Solution

• This is mostly just an ellipse in 3d or a weird sphere. Most of the code was stolen from these two
• Caveat: The formula for calculating the area of an ellipsoid is pretty complex and performance is bad. Wikipedia mentions an approximation formula which should probably be fine for most game engine use cases so I chose this for now
• Implementing the nearest_point function that the sphere has is also pretty hard for the ellipsoid so I left it out for now. I think it's not that essential. Potentially we could implement it with an euler approximation but I'm shying a bit away from iterative algorithms in the math library since I want to keep things snappy

Testing

• Added some unit tests.
• Added the new primitives to the primitive example

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Showcase

The new things in the primitives examples: