Require a "Wrapper" feature

[jeffchy]

It will be perfect to have a wrapper function to turn the model into the vllm-enhanced model. (like PEFT).
It is useful if we have a lora model, we can "merge_and_unload" it with the base model, and then wrap it, or in the case that we need to pull from some specific model revision from HF.

[hmellor]

@simon-mo is this a feature you'd like to see implemented?