Support NonZero constants in integer_const 17481

[arunsingh]

changelog: Improve internal constant evaluation for standard-library NonZero values

Fixes #17481.

Extends clippy_utils::consts::integer_const to read scalar-backed constants whose resolved type is core::num::NonZero<T>, including aliases such as NonZeroU32. General ADT evaluation remains unchanged.

Validation:

• cargo test -p clippy_utils --lib integer_const
• cargo dev fmt --check
• git diff --check
• cargo check -p clippy_utils
• cargo check -p clippy_lints
• cargo dev dogfood
• cargo test

[rustbot]

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[arunsingh]

@rustbot ready

[qdot3]

Sorry for the confusion. I was referring to NonZero::BITS in #17481.