Core implementation of JinaBert. This is referenced by the other models.

• Small: https://huggingface.co/jinaai/jina-embeddings-v2-small-en
• Base: https://huggingface.co/jinaai/jina-embeddings-v2-base-en
• Large: https://huggingface.co/jinaai/jina-embeddings-v2-large-en