* first v of vit shardformer
* keep vit
* update
* vit shard add vitattention vitlayer
* update num head shard para
* finish test for vit
* add new_model_class & postprocess
* add vit readme
* delete old files & fix the conflict
* fix sth
* add layernorm to bert
* add layernorm test
* add layernorm test with load state dict
* add use_mixedfusedLN in shard config
* refactor policy to support fused_layernorm