new models + various fixes

This version improves in a lot of tiny details and it has the following major features:

1. Supporting embeddings using any model from the Sentence BERT library.
2. Codeless dataset creation for (almost) any dataset in the IR-datasets library.
3. Improved re-ranking model zoo, including:

• COLBERT (in the re-ranking mode)
• Any sentence BERT bi-encoder
• PARADE models & Longformer