WebDriver: Implement POST /session/{id}/forward endpoint

Author: https://github.com/moustafaraafat
Commit: a4fa604bde
Pull-request: https://github.com/SerenityOS/serenity/pull/15623
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/TobyAsE ✅

Userland/Services/WebDriver/Session.h

@@ -39,6 +39,7 @@ public:
     ErrorOr<JsonValue, HttpError> get_title();
     ErrorOr<JsonValue, HttpError> refresh();
     ErrorOr<JsonValue, HttpError> back();
+    ErrorOr<JsonValue, HttpError> forward();
 
 private:
     NonnullRefPtr<Client> m_client;