Use a number-smart sorting function for imports

[scottmcm]

Today, rustfmt reorders like this:

-use crate::num::{NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroIsize};
+use crate::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};

Playground to repro: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=69ff891f23f740c0602c91da88d40b3f

I consider that ordering materially worse, since it's the biggest one, then three in ascending order, then the smallest one.

Because in type names people are unlikely to zero-pad, I think rustfmt should choose an ordering predicate that can pick up on numbers and sort that part numerically, as opposed to lexicographically-on-the-decimal-representation.

(Maybe do this along with #5075 that's also about the sorting predicate.)

[calebcartwright]

Thanks, though going to close as a duplicate in a desire to attempt to consolidate the discussion on this recurring topic in one place (#5075 (comment))

[scottmcm]

Ah, I see it came up in #3242 too.