Support for baichuan models

[Mr-Nineteen]

Support for baichuan models，model address：

• https://huggingface.co/baichuan-inc/Baichuan-13B-Chat
• https://huggingface.co/baichuan-inc/Baichuan-13B-Base

[WoosukKwon]

Hi @Mr-Nineteen, thanks for the request! To my understanding, Baichuan's architecture is GPT + ALiBi (which is essentially the same as BLOOM and MPT), right? If yes, it'll be pretty easy to add the model to vLLM.

[zhuohan123]

Fixed by #643