Add Annulus primitive to bevy_math::primitives

[Chubercik]

Objective

• Tracking Issue: Primitive Shapes #10572

There is no 2D primitive available for the common shape of an annulus (ring).

Solution

This PR introduces a new type to the existing math primitives:

• Annulus: the region between two concentric circles

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Changelog

Added

• Annulus primitive to the bevy_math crate
• Annulus tests (diameter, thickness, area, perimeter and closest_point methods)

[alice-i-cecile]

Some feedback on documentation :) Useful shape though!

[pablo-lua]

I think we can implement Meshable for this? Not sure what are the requirements.
The overall looks good!

[Jondolf]

I like this! Left some suggestions though :)

I think we can leave meshing, gizmos, and bounding volumes for follow-ups. I don't see a reason to block on them, and adding everything at once can add friction to reviews, as we've seen with some other primitives.

[Chubercik]

Alright, every comment should've been accounted for :)

As of right now, I don't really see the reason for using Circles (only the diameter() method got something out of it), but I assume this will come in handy when we start adding more stuff onto the Annulus struct (e.g. meshing, gizmos, bounding, etc.).

[Jondolf]

I'm somewhat deliberating if we should call this Annulus or Ring; the latter would be more approachable and perhaps more obvious, but could have some ambiguities (2D or 3D?), while Annulus is more mathematically accurate and unambiguously 2D.

I'm fine with either name, and Ring is already a doc alias here so I think Annulus should be fine.

As of right now, I don't really see the reason for using Circles (only the diameter() method got something out of it)

Yeah it didn't end up being very useful here specifically, but even just for users it could be nice to have methods for getting the diameter/area/perimeter of the inner and outer circle. We could add these methods to Annulus directly, but I generally prefer reusing the existing primitives for things like this (where reasonable).

[Chubercik]

I went with Annulus instead of Ring by default after googling "ring", "math ring", "geometry ring" - almost all resulting images are those of jewellery, so I thought there was a preconceived notion that a ring is understood commonly as a 3D object (a torus, perhaps).

(searching for "ring math" and "ring geometry" is an improvement, but there is still finger bling to be found here and there 😁)

[pablo-lua]

TBH, After I learned the math explanation, I found Annulus more fit. At the same time, I didn't understand it at first. Maybe we can have a link to a wikipedia explanation or something.
(But I don't know if that's needed, after all, we say that its basically a ring but 2d)