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/postgres-protocol2/src/message/backend.rs

@@ -1,13 +1,13 @@
 #![allow(missing_docs)]
 
+use std::io::{self, Read};
+use std::ops::Range;
+use std::{cmp, str};
+
 use byteorder::{BigEndian, ByteOrder, ReadBytesExt};
 use bytes::{Bytes, BytesMut};
 use fallible_iterator::FallibleIterator;
 use memchr::memchr;
-use std::cmp;
-use std::io::{self, Read};
-use std::ops::Range;
-use std::str;
 
 use crate::Oid;
 

libs/proxy/postgres-protocol2/src/message/frontend.rs

@@ -1,13 +1,13 @@
 //! Frontend message serialization.
 #![allow(missing_docs)]
 
+use std::error::Error;
+use std::{io, marker};
+
 use byteorder::{BigEndian, ByteOrder};
 use bytes::{Buf, BufMut, BytesMut};
-use std::error::Error;
-use std::io;
-use std::marker;
 
-use crate::{write_nullable, FromUsize, IsNull, Oid};
+use crate::{FromUsize, IsNull, Oid, write_nullable};
 
 #[inline]
 fn write_body<F, E>(buf: &mut BytesMut, f: F) -> Result<(), E>