* Add support for multiturn fewshot examples and chat templates
Added two new arguments to the evaluation script: `--fewshot-as-multiturn` and `--apply-chat-template` which correspond to lm_eval options of similar names and are very often used to ensure apples-to-apples comparisons of lm_evaluation results
* Add HF overrides for methods needed by added options
* don't add duplicate bos
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Co-authored-by: Awni Hannun <awni@apple.com>