llama : add phi3 support (#6852)
* add explicit phi3 support
* add explicit phi3 support
* remove unused code
* convert : add BOS token
* llama : match EOT token <|end|>
* llama : minor / style
* llama : tabs -> spaces
* convert : fix lint checks
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Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
