Auto merge of #125443 - nnethercote:rustfmt-use-decls, r=lcnr,cuviper,GuillaumeGomez

rustfmt `use` declarations

This PR implements https://github.com/rust-lang/compiler-team/issues/750, which changes how `use` declarations are formatted by adding these options to `rustfmt.toml`:
```
group_imports = "StdExternalCrate"
imports_granularity = "Module"
```

r? `@ghost`

1 files changed, 2 insertions, 1 deletions

diff --git a/library/std/tests/env.rs b/library/std/tests/env.rs
index a1ca85c2145..4e472b4ce99 100644
--- a/library/std/tests/env.rs
+++ b/library/std/tests/env.rs
@@ -4,9 +4,10 @@ use std::ffi::{OsStr, OsString};
 use rand::distributions::{Alphanumeric, DistString};
 
 mod common;
-use common::test_rng;
 use std::thread;
 
+use common::test_rng;
+
 #[track_caller]
 fn make_rand_name() -> OsString {
     let n = format!("TEST{}", Alphanumeric.sample_string(&mut test_rng(), 10));