Added a simpler one-time chat api

[Binozo]

Hello 🤠

I needed a simpler api to one-time chat with my ollama endpoint
Hope it fits well

[awaescher]

Hey Binozo, thanks for helping out. May I ask what the intention is for the changes you added?

[Binozo]

In my use case I built a RAG system and need a simple way to chat with a model once, because I got one question and I want one answer. The way through IAsyncEnumerable<ChatResponseStream?> Chat was a little confusing for me 😅

[awaescher]

Hm, I guess you would have needed StreamToEnd() if I understand correctly. This is available as extension method to IAsyncEnumerable<T>. See the announcement of version 3.0.

[Binozo]

Oh I wan't aware of that, thanks for the clarification!