Add geometric primitives to bevy_math::prelude

[Jondolf]

Objective

Currently, the primitives module is inside of the prelude for bevy_math, but the actual primitives are not. This requires either importing the shapes everywhere that uses them, or adding the primitives:: prefix:

let rectangle = meshes.add(primitives::Rectangle::new(5.0, 2.5));

(Note: meshing isn't actually implemented yet, but it's in #11431)

The primitives are meant to be used for a variety of tasks across several crates, like for meshing, bounding volumes, gizmos, colliders, and so on, so I think having them in the prelude is justified. It would make several common tasks a lot more ergonomic.

let rectangle = meshes.add(Rectangle::new(5.0, 2.5));

Solution

Add primitives::* to bevy_math::prelude.