`from_bevy_mesh` doesn't support unindexed glTF

https://github.com/dimforge/bevy_rapier/blob/6aa960b611b64cdd4d659afcf2fa67429433ee09/src/geometry/collider_impl.rs#L739-L743

If `mesh.indices()` doesn't exist, function returns None.

Turns out, indices can be absent from glTF, and the file will still be valid. In this case, bevy Mesh wouldn't have any indices either (but bevy would display it just fine). You can search the internet by keywords "unindexed mesh gltf", and it's full of bug reports about lack of support from various projects...

I'm using osm2world, and it turns out that it generates unindexed meshes, so... Any ideas how to implement it?