* [Refactor] Refactor the import rule

* minor refinement

* add a comment

* fix missing device ids in wrap_model

* clean the code

* use default broadcast_buffers

* refine MMSeparateDistributedDataParallel

* rename tmp variable

* refine docstring

* add type hints

* refactor docstring of ddp model

* add  arg in docstring

* minor refine

* better ddp link

* assert image shape before forward

* add unit test

* enhance error message

* allow gray image input

* fix as comment

* fix unit test

* fix unit test

* modify cuda() to to()

* rollback load_checkpoint

* refine runner

* add TODO

* [Feat] Support FSDP Training

* fix version comparison

* change param format and move `FSDP_WRAP_POLICY` to wrapper file

* add docstring and type hint,reformat code

* fix type hint

* fix typo, reformat code

* merge context

* update unit test

* add docstring

* fix bug in AmpOptimWrapper

* add docstring for backward

* add warning and docstring for accumuate gradient

* fix docstring

* fix docstring

* add params_group method

* fix as comment

* fix as comment

* make default_value of loss_scale to dynamic

* Fix docstring

* decouple should update and should no sync

* rename attribute in OptimWrapper

* fix docstring

* fix comment

* fix comment

* fix as comment

* fix as comment and add unit test

* [Fix] Fix image dtype when enable_normalize=False.

* update ut

* move to collate

* update ut

* add module list

* add module list

* fix docstring

* fix BaseDataPreprocessor

* fix BaseDataPreprocessor

* change device type to torch.device

* change device type to torch.device

* fix cpu method of base model

* Allow ImgDataPreprocessor do not normalize

* remove unnecessary type ignore

* make mean and std optional

* refine docstring

* fix BaseDataPreprocessor

* fix BaseDataPreprocessor

* change device type to torch.device

* change device type to torch.device

* fix cpu method of base model

* [Enhance] Optimize parameter updating speed in AveragedModel.

* add docstring

* add base model, ddp model and unit test

* add unit test

* fix unit test

* fix docstring

* fix cpu unit test

* refine base data preprocessor

* refine base data preprocessor

* refine interface of ddp module

* remove optimizer hook

* add forward

* fix as comment

* fix unit test

* fix as comment

* fix build optimizer wrapper

* rebase main and fix unit test

* stack_batch support stacking ndim tensor, add docstring for merge dict

* fix lint

* fix test loop

* make precision_context effective to data_preprocessor

* fix as comment

* fix as comment

* refine docstring

* change collate_data output typehints

* rename to_rgb to bgr_to_rgb and rgb_to_bgr

* support build basemodel with built DataPreprocessor

* fix as comment

* fix docstring

* [Fix] Fix some bugs in hooks and runner.

* fix markdown

* fix latex formula

* resolve comments

* [Feature] Support EMA and SWA.

* add ema hook

* add avg model ut

* add more unit tests

* resolve comments

* fix warmup ema

* rename

* fix comments

* add assert

* fix typehint

* add comments

* [Fix]: Fix model_wrapper and add DistSamplerSeedHook as default hook.

* add comments

* add mmddp

* update

* update code

* update unittest

* fix comment