[WIP] Format interior of brace macros

[nhynes]

Resolves #3445.

The primary change is in macros.rs and un-skips formatting of brace macros (simply removes the conditional).
The other change is in imports.rs and address what seems to be a general bug in which Use statements aren't formatted when there's an empty attrs array. Perhaps it would be better to address the underlying cause of Some([]) (or even why use Option when an empty Vec has the same semantics as None).

[scampi]

Sorry for the delay in commenting! Can you move the change of imports.rs into a separate PR and add a test for it ? This way we could solve the problem you found while still pondering the formatting of brace macros.

[nhynes]

Looks like someone already applied the fix to imports. Still would be nice to have formatting inside of brace macros when the interior is rust code (e.g., in quote!).

[topecongiro]

My apologies for the late review.

The primary change is in macros.rs and un-skips formatting of brace macros (simply removes the conditional).

IMHO, the current macro formatting is not good enough for enabling this. As such, I am closing this PR as won't merge. Thanks!