refactor(rust): always allow Cargo.lock file

[carlocorradini]

Reasons for making this change:

Rust advice for Cargo.lock file is to do whatever is best for their project.
From Rust nightly 2023-08-24, command cargo new no longer ignores Cargo.lock for libraries.
Therefore, the Cargo.lock file should not be ignored.

Links to documentation supporting these rule changes:

Official Rust Blog: https://blog.rust-lang.org/2023/08/29/committing-lockfiles.html
Official Rust Doc: https://doc.rust-lang.org/nightly/cargo/faq.html#why-have-cargolock-in-version-control

[bensheldon]

Closed by #4350