Uplift clippy::cmp_nan lint

[Urgau]

This PR aims at uplifting the clippy::cmp_nan lint into rustc.

invalid_nan_comparisons

(deny-by-default) (warn-by-default)

The invalid_nan_comparisons lint checks comparison with f32::NAN or f64::NAN as one of the operand.

Example

let a = 2.3f32;
if a == f32::NAN {}

Explanation

NaN does not compare meaningfully to anything – not even itself – so those comparisons are always false.

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Mostly followed the instructions for uplifting a clippy lint described here: #99696 (review)

@rustbot label: +I-lang-nominated
r? compiler