[RFC] Refactor chat template and remove model name from engine config

[AllentDan]

Motivation

• Decoupling dialogue templates from the inference engine.
• Reduce the barrier to adding new dialogue templates.
• Remove model_name from EngineConfig to avoid redundant specification.
• Support external dialogue templates compatible with Transformers.

Major features

• The Tokenizer class supports Transformers’ Jinja dialogue templates.
• Original model.get_prompt will be moved to Tokenizer.apply_chat_template
• model_name is removed from TurbomindEngineConfig and PytorchEngineConfig.

How to use

For api_server, to use an extra template, commands could be:

lmdeploy serve api_server $MODEL_PATH --chat-template $JINJIA

For APIs like pipeline, we are going to provide documents to show how to add a chat template in python or Jinjia. The codes will be:

chat_template = PythonTemplate() # or a function or a Jinjia str or file path
input_inds = tokenizer.apply_chat_template(messages, chat_template=chat_template)
pipeline(input_ids)