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/protocol2.rs

@@ -407,7 +407,7 @@ mod tests {
     use tokio::io::AsyncReadExt;
 
     use crate::protocol2::{
-        read_proxy_protocol, ConnectHeader, LOCAL_V2, PROXY_V2, TCP_OVER_IPV4, UDP_OVER_IPV6,
+        ConnectHeader, LOCAL_V2, PROXY_V2, TCP_OVER_IPV4, UDP_OVER_IPV6, read_proxy_protocol,
     };
 
     #[tokio::test]