Coupons: small refactor.

[liorgold2]

Stack:

• Rename FunctionCallConcreteLibfunc to SignatureAndFunctionConcreteLibfunc. #4615
• Coupons: small refactor. #4614 ⬅

⚠️ Part of a stack created by spr. Do not merge manually using the UI - doing so may have unexpected results.

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This change is 

[orizi]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @liorgold2)

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crates/cairo-lang-sierra/src/extensions/modules/function_call.rs line 73 at r1 (raw file):

        let [GenericArg::UserFunc(function_id)] = args else {
            return Err(SpecializationError::UnsupportedGenericArg);
        };

Suggestion:

        let function_id = args_as_single_user_func(args)?;

[liorgold2]

Reviewable status: 2 of 3 files reviewed, 1 unresolved discussion (waiting on @orizi)

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crates/cairo-lang-sierra/src/extensions/modules/function_call.rs line 73 at r1 (raw file):

        let [GenericArg::UserFunc(function_id)] = args else {
            return Err(SpecializationError::UnsupportedGenericArg);
        };

Done.

[orizi]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @liorgold2)

[orizi]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @liorgold2)

[liorgold2]

Reviewed 1 of 1 files at r4, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @liorgold2)