Function dict_to_csv 

pub fn dict_to_csv<S: DictionarySerializer>(
    prefix_dict: &PrefixDict,
    words_idx_data: &[u8],
    words_data: &[u8],
    serializer: &S,
) -> LinderaResult<Vec<String>>

Converts dictionary to csv.

The third column (right_id) cannot be recovered because it is already lost while building the dictionary.