Bump warp and begin axum migration (#9001)

- Bump `warp` to 0.4. This unifies `warp` and `axum` onto the same `http`, `hyper`, `h2`, `rustls`, etc versions.
- Create `axum_utils` which contain common functions and types
- Begins migration of all HTTP API servers from warp to axum


Co-Authored-By: Mac L <mjladson@pm.me>

beacon_node/http_metrics/tests/tests.rs

@@ -34,7 +34,7 @@ async fn returns_200_ok() {
             // It's not really interesting why this triggered, just that it happened.
             let _ = shutdown_rx.await;
         };
-        let (listening_socket, server) = http_metrics::serve(ctx, server_shutdown).unwrap();
+        let (listening_socket, server) = http_metrics::serve(ctx, server_shutdown).await.unwrap();
 
         tokio::spawn(server);