Rollup merge of #93759 - dtolnay:usetree, r=nagisa

Rollup merge of #93759 - dtolnay:usetree, r=nagisa

Pretty print ItemKind::Use in rustfmt style

This PR backports the formatting for `use` items from https://github.com/dtolnay/prettyplease into rustc_ast_pretty.

Before:

```rust
use core::{cmp::{Eq, Ord, PartialEq, PartialOrd},
    convert::{AsMut, AsRef, From, Into},
    iter::{DoubleEndedIterator, ExactSizeIterator, Extend, FromIterator,
    IntoIterator, Iterator},
    marker::{Copy as Copy, Send as Send, Sized as Sized, Sync as Sync, Unpin
    as U}, ops::{*, Drop, Fn, FnMut, FnOnce}};
```

After:

```rust
use core::{
    cmp::{Eq, Ord, PartialEq, PartialOrd},
    convert::{AsMut, AsRef, From, Into},
    iter::{
        DoubleEndedIterator, ExactSizeIterator, Extend, FromIterator,
        IntoIterator, Iterator,
    },
    marker::{
        Copy as Copy, Send as Send, Sized as Sized, Sync as Sync, Unpin as U,
    },
    ops::{*, Drop, Fn, FnMut, FnOnce},
};
```