[Feature]: Chat inputs to AsyncLLMEngine

[sfc-gh-mkrubinski]

🚀 The feature, motivation and pitch

Currently, only the LLM class meant for offline inference supports the chat method.
Are there any plans to implement a similar method for AsyncLLMEngine, besides the existing generate?
Alternatively, is there any work on extending the PromptType acceptable by generate to include more prompt variants, such as chat conversations?

Alternatives

No response

Additional context

No response

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[DarkLight1337]

I think there is not much reason to do this now because the interface of async engine will change significantly in V1. Maybe after the API is more stable? cc @robertgshaw2-redhat