Implement PartialEq for Collider

[RJ]

All the bevy_xpbd components I'm using implement PartialEq except for Collider.

Having PartialEq is really useful for various netcode bits that check what's changed in generic systems.

Collider is a wrapper over parry's SharedShape, and not all parry Shapes implement PartialEq

For those that do, i'm using it. For the rest, i'm comparing what is necessary manually – eg, border radius for rounded versions of shapes.

I took the big match on shape types from the implementation of fmt::Debug for Collider, so PartialEq will work for all the same shapes.

[Jondolf]

Thanks! Ideally, this would be implemented for Parry's SharedShape directly, but this works as a workaround for now. We could also make a PR to add this to Parry though.

[RJ]

dimforge/parry#162