Extending the neural TN/ITN models for other languages
https://github.com/NVIDIA/NeMo/pull/2415 was mainly targetting English. This PR extends it to support other languages.

- [x] Testing the new code on Russian
- [x] Testing the new code on German

Results on Google Russian dataset and internal German dataset:
- Russian Duplex System. TN accuracy: 96.20%. ITN accuracy: 85.57%
- German Duplex System. TN accuracy: 94.38%. ITN accuracy: 79.89%