Upgrade proxy crates to edition 2024 (#10942)

This upgrades the `proxy/` crate as well as the forked libraries in
`libs/proxy/` to edition 2024.

Also reformats the imports of those forked libraries via:

```
cargo +nightly fmt -p proxy -p postgres-protocol2 -p postgres-types2 -p tokio-postgres2 -- -l --config imports_granularity=Module,group_imports=StdExternalCrate,reorder_imports=true
```

It can be read commit-by-commit: the first commit has no formatting
changes, only changes to accomodate the new edition.

Part of #10918

libs/proxy/tokio-postgres2/src/error/mod.rs

@@ -1,10 +1,10 @@
 //! Errors.
 
+use std::error::{self, Error as _Error};
+use std::{fmt, io};
+
 use fallible_iterator::FallibleIterator;
 use postgres_protocol2::message::backend::{ErrorFields, ErrorResponseBody};
-use std::error::{self, Error as _Error};
-use std::fmt;
-use std::io;
 
 pub use self::sqlstate::*;