Crates are incompatible with `cargo vendor`

[SkyLeite]

Due to the bevy_rapier2d and bevy_rapier3d packages pointing to source files outside of the crate scope in Cargo.toml, attempting to use either of them with the cargo vendor command results in the following error:

warning: fge_core v0.1.0 ignoring invalid dependency bevy_rapier2d which is missing a lib target

One way to fix this would be to introduce a third crate (maybe bevy_rapier_common) which would then be added as a dependency for bevy_rapier2d and bevy_rapier3d.