Create a `LabelList` from `state`.

def load_state(cls, path:PathOrStr, state:dict) -> 'LabelList':
        "Create a `LabelList` from `state`."
        x = state['x_cls']([], path=path, processor=state['x_proc'], ignore_empty=True)
        y = state['y_cls']([], path=path, processor=state['y_proc'], ignore_empty=True)
        res = cls(x, y, tfms=state['tfms'], tfm_y=state['tfm_y'], **state['tfmargs']).process()
        if state.get('tfms_y', False):    res.tfms_y    = state['tfms_y']
        if state.get('tfmargs_y', False): res.tfmargs_y = state['tfmargs_y']
        if state.get('normalize', False): res.normalize = state['normalize']
        return res