[req] drop from_controller on non WebRequest object (Closes #2901079) The `controller` concept is purely a web things. It does not belong to generic `req` object. The `build_url` code is slightly changed to handle that. This probably requires extended cleanup later. This is a barely used and very internal API. No deprecation period

raise NotImplementedError("Cannot migrate such an old version. Use intermediate Cubiweb version (try 3.16.x)")