Process correctly label ids dataset parameter + standardize type of label ids model attribute + minor changes (error messages, typing)
1. If  `BertPunctuationCapitalizationDataset.__init__` arguments `punct_label_ids` and `capit_label_ids` are  `DictConfig`s, then transform them to dictionaries.
2. Make sure that `PunctuationCapitalizationModel` attributes `punct_label_ids` and `capit_label_ids` are always dictionaries and not `DictConfig`s. Previously, type of these attributes varied depending on where the attributes are set.
3. Add more typing and improve error messages.