[TTS] New structure for TTS datasets in scripts/dataset_processing, VocoderDataset, update TTSDataset
- [x] Create unify downloading and processing TTS datasets in `scripts/dataset_proccesing/tts`
- [x] Add `VocoderDataset`
- [x] Fix problem with collision in name (e.g. LibriTTS suffers) for supplementary data in `TTSDataset`
- [x] Other minor updates in `collection.tts.torch` 


Signed-off-by: Oktai Tatanov <oktai.tatanov@gmail.com>