feature: from use statement, add crate to cargo.toml

use crate_x::Fred;

If we are in a workspace we probably have this crate ( or crate-x ) already imported somewhere in another Cargo.toml.

Would be pretty cool to alt-enter the use statement and say "yes please, try to add this crate to my cargo.toml" (if multiple versions are in use could default to the highest),

Would be great for keeping people in the flow...