server : various fixes (#10704)

* server : various fixes

ggml-ci

* server : show curent seed in slot_params

ggml-ci

* fix /slots endpoint

* Update examples/server/server.cpp

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* server : reflect endpoint response changes in the readme

ggml-ci

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Co-authored-by: Xuan Son Nguyen <son@huggingface.co>
Co-authored-by: Xuan Son Nguyen <thichthat@gmail.com>