Added warnings for unused trait imports as well.

[orizi]

This change is 

[gilbens-starkware]

Reviewed 45 of 45 files at r1, all commit messages.
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crates/cairo-lang-semantic/src/expr/compute.rs line 1698 at r1 (raw file):

/// call and Index operator differs in the diagnostics they emit. The function returns the
/// function_id to call, the self argument, with snapshots added if needed, and the mutability of
/// the self argument.

Suggestion:

/// call and Index operator differs in the diagnostics they emit. The function returns the
/// function_id to call, the trait containing the function, the self argument, with snapshots added if needed, and the mutability of
/// the self argument.

[orizi]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @gilbens-starkware)

---

crates/cairo-lang-semantic/src/expr/compute.rs line 1698 at r1 (raw file):

/// call and Index operator differs in the diagnostics they emit. The function returns the
/// function_id to call, the self argument, with snapshots added if needed, and the mutability of
/// the self argument.

Done.

[gilbens-starkware]

Reviewed 1 of 1 files at r2, all commit messages.
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