WebDriver: Pass --enable-qt-networking when launching Ladybird

Using Qt networking when running tests improves speed significantly.
The time to run the subset of tests we run on CI drops from 47.2
seconds to 8.2 seconds on my machine.

Ladybird/WebDriver/main.cpp

@@ -47,6 +47,7 @@ static ErrorOr<pid_t> launch_browser(ByteString const& socket_path)
 
     arguments.append("--allow-popups");
     arguments.append("--force-new-process");
+    arguments.append("--enable-qt-networking");
 
     arguments.append("about:blank");