Additional python debug output on missing __dict__

[EinarElen]

When working on LDMX-sw, it isn't uncommon to break your python configuration files. One of the most annoying to debug is the missing dict one. I think it would be good to print a repr of the PyObject* before throwing the exception (or include the repr in the exception message).

Taking inspiration from the existing getPyString, something equivalent to

static void pretty_print(PyObject* object) {
  PyObject* repr = PyObject_Repr(object);  // Get string representation
  if (repr != nullptr) {
    const char* str = PyUnicode_AsUTF8(repr);  
    if (str != nullptr) {
      std::cout << "Python object: " << str
                << std::endl;
    }
    Py_XDECREF(repr);
  }
}

should probably do the trick