feat: add support for KV cache quantization options (#1307)

* add KV cache quantization options

https://github.com/abetlen/llama-cpp-python/discussions/1220
https://github.com/abetlen/llama-cpp-python/issues/1305

* Add ggml_type

* Use ggml_type instead of string for quantization

* Add server support

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Co-authored-by: Andrei Betlen <abetlen@gmail.com>