http: Refactor construction of HTTP clients with a proxy (#14911)

This PR refactors the `http` crate to expose a better way of
constructing an `HttpClient` that contains a proxy.

Release Notes:

- N/A

crates/node_runtime/src/node_runtime.rs

@@ -269,7 +269,16 @@ impl NodeRuntime for RealNodeRuntime {
             }
 
             if let Some(proxy) = self.http.proxy() {
-                command.args(["--proxy", proxy]);
+                // Map proxy settings from `http://localhost:10809` to `http://127.0.0.1:10809`
+                // NodeRuntime without environment information can not parse `localhost`
+                // correctly.
+                // TODO: map to `[::1]` if we are using ipv6
+                let proxy = proxy
+                    .to_string()
+                    .to_ascii_lowercase()
+                    .replace("localhost", "127.0.0.1");
+
+                command.args(["--proxy", &proxy]);
             }
 
             #[cfg(windows)]