[Rust CI] Avoid multiple imports of the same dependency

[drewrelmas]

We should detect when a crate is imported multiple times in different crates within the same workspace. In such cases, the best practice is to move the dependency declaration to the main Cargo.toml so that there is only one version.

There might already be some cargo commands that handle this, otherwise, another option would be to extend what we have in our xtask check/structure.

Upon cursory search, cargo-autoinherit might help.