Auto merge of #16489 - jdm:http-response, r=asajeffrey

Show HTTP response headers in debug output.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [x] These changes do not require tests because they are changing informative debug output.

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components/net/http_loader.rs

@@ -1095,6 +1095,13 @@ fn http_network_fetch(request: &Request,
         Err(error) => return Response::network_error(error),
     };
 
+    if log_enabled!(log::LogLevel::Info) {
+        info!("response for {}", url);
+        for header in res.response.headers.iter() {
+            info!(" - {}", header);
+        }
+    }
+
     let mut response = Response::new(url.clone());
     response.status = Some(res.response.status);
     response.raw_status = Some((res.response.status_raw().0,