[example] llama2 add fine-tune example (#4673)

* [shardformer] update shardformer readme

[shardformer] update shardformer readme

[shardformer] update shardformer readme

* [shardformer] update llama2/opt finetune example and shardformer update to llama2

* [shardformer] update llama2/opt finetune example and shardformer update to llama2

* [shardformer] update llama2/opt finetune example and shardformer update to llama2

* [shardformer] change dataset

* [shardformer] change dataset

* [shardformer] fix CI

* [shardformer] fix

* [shardformer] fix

* [shardformer] fix

* [shardformer] fix

* [shardformer] fix

[example] update opt example

[example] resolve comments

fix

fix

* [example] llama2 add finetune example

* [example] llama2 add finetune example

* [example] llama2 add finetune example

* [example] llama2 add finetune example

* fix

* update llama2 example

* update llama2 example

* fix

* update llama2 example

* update llama2 example

* update llama2 example

* update llama2 example

* update llama2 example

* update llama2 example

* Update requirements.txt

* update llama2 example

* update llama2 example

* update llama2 example