FIX: NegMultiply should preserve parenthesis when method is called

[Zarathustra2]

Hi,

I noticed that the lint neg_multiply generates bad code when we call a method on the expression.
Consider ((a.delta - 0.5).abs() * -1.0).total_cmp(&1.0). Currently this would be changed by clippy to -(a.delta - 0.5).abs() .total_cmp(&1.0) - which does not compile because we are trying to negate an ordering enum - but what we really want is (-(a.delta - 0.5).abs()).total_cmp(&1.0).

This PR fixes this.

changelog: [neg_multiply] does not remove parenthesis anymore if a method is being called on the affected expression

NOTE: This is the first time I am contributing to clippy or the rust repo in general. So I am not sure whether my approach to fixing this issue is goo, if there are better solutions or if I missed something.

Thanks & hope you have a good day,
Dario

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