pub fn new(
        package: PackageMetadata<'g>,
        labels: impl IntoIterator<Item = FeatureLabel<'g>>,
    ) -> Self {
        Self {
            package,
            labels: labels.into_iter().collect(),
        }
    }
Creates a new `FeatureList` from a package and an iterator over feature labels.
guppy/src/graph/feature/feature_list.rs