Generate `is_copy_constructible<T>` to tell pybind11 that `T` is not copyable.
Generate `is_copy_constructible<T>` to tell pybind11 that `T` is not copyable.

For types that contains `vector<unique_ptr<T>>` as attributes, `std::is_copy_constructible` might return incorrect result. See cl/452430092 for an example.

PiperOrigin-RevId: 453812883

google/clif,google/clif,google/clif