Let's add supports for other LLMs

For some reasons, some users can not use OpenAI.

We should add supports for other LLMs. Open source LLMs are preferred.

For example:

- https://github.com/tatsu-lab/stanford_alpaca
- https://github.com/ggerganov/llama.cpp
- https://github.com/LC1332/Chinese-alpaca-lora 
- https://github.com/THUDM/ChatGLM-6B
