llama : add EXAONE model support (#9025)

* add exaone model support

* add chat template

* fix whitespace

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

* add ftype

* add exaone pre-tokenizer in `llama-vocab.cpp`

Co-Authored-By: compilade <113953597+compilade@users.noreply.github.com>

* fix lint

Co-Authored-By: compilade <113953597+compilade@users.noreply.github.com>

* add `EXAONE` to supported models in `README.md`

* fix space

Co-authored-by: compilade <git@compilade.net>

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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
Co-authored-by: compilade <113953597+compilade@users.noreply.github.com>
Co-authored-by: compilade <git@compilade.net>