cargo_util: simplified cargo bbclass for crates
cargo_util: simplified cargo bbclass for crates

The existing cargo class attempts to jump through a few hoops for
settings that are not necessarily with newer versions of cargo.

jmesmon/meta-rust,meta-rust/meta-rust,starlab-io/meta-rust,meta-rust/meta-rust,meta-rust/meta-rust,jmesmon/meta-rust,starlab-io/meta-rust,meta-rust/meta-rust,cardoe/meta-rust,jmesmon/meta-rust,meta-rust/meta-rust,jmesmon/meta-rust,cardoe/meta-rust,cardoe/meta-rust,cardoe/meta-rust