`imports_granularity` is not respected for `#[cfg]`'d items

[clarfonthey]

Example with imports_granularity = "crate". The following:

#[cfg(true)]
use std::{cmp::Ordering, hash::Hash, hash::Hasher};
use core::{cmp::Ordering, hash::Hash, hash::Hasher};

will normalise to:

#[cfg(true)]
use std::{cmp::Ordering, hash::Hash, hash::Hasher};
use core::{cmp::Ordering, hash::{Hash, Hasher}};

Note that the desire to avoid messing with cfgs is too conservative here: the imports are not grouped in the same way.