Add CLI command to create LangSmith datasets

1. Set the ELI5_LANGCHAIN_API_KEY env variable:

   ELI5_LANGCHAIN_API_KEY="<your_langsmith_api_key>"

2. Run poetry install
3. Run poetry run eli5 --help
4. Run poetry run eli5 datasets create --help
5. To create the dataset:

   poetry run eli5 datasets create duo_chat.react_tool_selection.1 ./datasets/duo_chat/react_tool_selection_v1.jsonl