* [fx] Use colossalai.utils.checkpoint to replace torch.utils.checkpoint for offload activation and add offload annotation recognition in codegen
* [fx] Use colossalai.utils.checkpoint to replace torch.utils.checkpoint for offload activation and add offload annotation recognition in codegen
* Modification of test and add TODO in codegen
* [fx] Modification of colossal ckpt usage
* [fx] add gpc.destroy() to test_codegen