* [Enhance] Enhance revert_sync_batchnorm and convert_sync_batchnorm

* [Enhance] Enhance revert_sync_batchnorm and convert_sync_batchnorm

* Fix unit test

* Add coments

* Refine comments

* clean the code

* revert convert_sync_batchnorm

* revert convert_sync_batchnorm

* refine comment

* fix CI

* fix CI

* [Feature] Support convert BN to SyncBN by config

* make unit test compatible with cpu

* Fix as comment

* fix unit test

* change signature of convert_sync_batchnorm: rename sync_bn to implemention

* fix unit test

* fix unit test

* Rename data to structure

* adjust the way to import module

* adjust the way to import module

* rename Structure to Data Structures in docs api

* rename structure to structures

* support using some modules of mmengine without torch

* fix circleci config

* fix circleci config

* fix registry ut

* minor fix

* move init method from model/utils to model/weight_init.py

* move init method from model/utils to model/weight_init.py

* move sync_bn to model

* move functions depending on torch to dl_utils

* format import

* fix logging ut

* add weight init in model/__init__.py

* move get_config and get_model to mmengine/hub

* move log_processor.py to mmengine/runner

* fix ut

* Add TimeCounter in dl_utils/__init__.py

* fix BaseDataPreprocessor

* fix BaseDataPreprocessor

* change device type to torch.device

* change device type to torch.device

* fix cpu method of base model

* 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