Fail on passing py::object with wrong Python type to py::object subclass using PYBIND11_OBJECT macro (#2349)

* Fail on passing py::object with wrong Python type to py::object subclass using PYBIND11_OBJECT macro

* Split off test_non_converting_constructors from test_constructors

* Fix test_as_type, as py::type constructor now throws an error itself if the argument is not a type

* Replace tp_name access by pybind11::detail::get_fully_qualified_tp_name

* Move forward-declaration of get_fully_qualified_tp_name to detail/common.h

* Don't add the builtins module name in get_fully_qualified_tp_name for PyPy

* Add PYBIND11_BUILTINS_MODULE macro, and use it in get_fully_qualified_tp_name