If we're only aligning enum discriminants that are "not too far apart
(length-wise)", then this works really well for enums with
consistently-long or consistently-short idents, but not for the mixed
ones.
However, consistently-long idents is somewhate of an uncommon case and
overlong idents may be allowed to be formatted suboptimally if that
makes mixed-length idents work better (and it does in this case).
Add `reorder_modules` config option.
Two things we must keep in mind when reordering modules:
1. We should not reorder modules with attributes, as doing so could
potentially break the code (e.g. `#[macro_use]`).
2. We should not reorder inline modules e.g. `mod foo { /* .. */ }`.
We should only reorder module declarations e.g. `mod foo;`.
Some open questions:
1. Should we bring modules with `pub` in front of those without `pub`
so that they stand out from others?
2. Instead of keeping modules with attributes in the same place,
can we bring them in front of others? Is this safe?
