llama : validate special token ids are in range when loading GGUF model (#3635)

* Add validation for special token ids to llama.cpp

Small optimization for llama_byte_to_token SPM mode

* Fix BPE newline check, only I could break something so simple

* Killll meeeeee

* Account for GGUF_KEY_KEY only setting when the key exists

* Minor code cleanups.

* Fix convert.py error msg when added tokens are out of range

* Make gguf SpecialVocab vocab size-aware

Update conversion scripts accordingly

* Avoid a string copy

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

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