* Prefilling assistant message in openai compatible API
* fixed indentation
* fixed code convention
* simplify method usage
* no more than one assistant message at end of messages
* merge checks into prefill code
* Update examples/server/utils.hpp
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Co-authored-by: matteo <matteo@naspc.lan>
Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>