Add ConvNeXt tiny and small pretrain  in22k
Add ConvNeXt tiny and small pretrain  in22k

Add ConvNeXt tiny and small pretrain  in22k from ConvNeXt  repo:
https://github.com/facebookresearch/ConvNeXt/commit/06f7b05f922e21914916406141f50f82b4a15852
rwightman/pytorch-image-models,rwightman/pytorch-image-models