[Rust] Unused variable False positive

**Description of the false positive**

The argument is being used in the body of the function but flagged unused.

**Code samples or links to source code**

This is one specific example https://github.com/microsoft/windows-drivers-rs/blob/main/crates/cargo-wdk/src/providers/fs.rs#L29

**URL to the alert on GitHub code scanning (optional)**
https://github.com/microsoft/windows-drivers-rs/security/code-scanning/5

However, false positives for the arguments are generated for all the methods in [this](https://github.com/microsoft/windows-drivers-rs/blob/main/crates/cargo-wdk/src/providers/fs.rs) module and other sibling modules ([exec](https://github.com/microsoft/windows-drivers-rs/blob/main/crates/cargo-wdk/src/providers/exec.rs), [metadata](https://github.com/microsoft/windows-drivers-rs/blob/main/crates/cargo-wdk/src/providers/metadata.rs) and [wdk_build](https://github.com/microsoft/windows-drivers-rs/blob/main/crates/cargo-wdk/src/providers/wdk_build.rs)).

Start with the flagged argument at crates/cargo-wdk/src/providers/fs.rs#L29 and inspect the linked CodeQL alert. Compare the usage there with the methods in the fs, exec, metadata, and wdk_build provider modules. Done means those used arguments are no longer reported as unused by code scanning.

Written by the indexing model from the issue text.