lugimzzz

WIP [llm]support dpo/kto pp

1

### PR types New features ### PR changes APIs ### Description 重构dpo trainer(还在开发中，未验证，请勿review)

【llm】remove prefix tuning

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### PR types Breaking changes ### PR changes Others ### Description 移除prefix tuning

[llm]support long sequence training

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### PR types New features ### PR changes Others ### Description 新增支持单机8卡 llama 128k训练 待解决问题： 1. 如果fuse_fused_head_and_loss_fn，开启pp和开eval的时候loss异常需要排查

[Readme] Add flash mask

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### PR types New features ### PR changes Others ### Description 新增flashmask使用示例脚本