feat: Add NonZero::<T>::from_str_radix

[sorairolake]

• ACP: ACP: Add NonZero::<T>::from_str_radix libs-team#548

This pull request adds a method to NonZero<T> that parses a non-zero integer from a string slice with digits in a given base.

When using the combination of int::from_str_radix and NonZero::<T>::new, IntErrorKind::Zero cannot be returned as an error. When using NonZero::<T>::from_str, IntErrorKind::Zero can be returned as an error, but this method cannot parse non-decimal integers.

NonZero::<T>::from_str_radix can return IntErrorKind::Zero as an error, and can parse both decimal integers and non-decimal integers.

Important

ACP has not yet been approved, and this must be approved before this pull request is ready for review.

[sorairolake]

@rustbot label +T-libs-api -T-libs
r? libs-api