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

proxy/src/rate_limiter/limit_algorithm.rs

@@ -5,8 +5,8 @@ use std::time::Duration;
 
 use parking_lot::Mutex;
 use tokio::sync::Notify;
-use tokio::time::error::Elapsed;
 use tokio::time::Instant;
+use tokio::time::error::Elapsed;
 
 use self::aimd::Aimd;