* Support multiple optimizers

* minor refinement

* improve unit tests

* minor fix

* Update unit tests for resuming or saving ckpt for multiple optimizers

* refine docstring

* refine docstring

* fix typo

* update docstring

* refactor the logic to build multiple optimizers

* resolve comments

* ParamSchedulers spports multiple optimizers

* add optimizer_wrapper

* fix comment and docstirng

* fix unit test

* add unit test

* refine docstring

* RuntimeInfoHook supports printing multi learning rates

* resolve comments

* add optimizer_wrapper

* fix mypy

* fix lint

* fix OptimizerWrapperDict docstring and add unit test

* rename OptimizerWrapper to OptimWrapper, OptimWrapperDict inherit OptimWrapper, and fix as comment

* Fix AmpOptimizerWrapper

* rename build_optmizer_wrapper to build_optim_wrapper

* refine optimizer wrapper

* fix AmpOptimWrapper.step, docstring

* resolve confict

* rename DefaultOptimConstructor

* fix as comment

* rename clig grad auguments

* refactor optim_wrapper config

* fix docstring of DefaultOptimWrapperConstructor

fix docstring of DefaultOptimWrapperConstructor

* add get_lr method to OptimWrapper and OptimWrapperDict

* skip some amp unit test

* fix unit test

* fix get_lr, get_momentum docstring

* refactor get_lr, get_momentum, fix as comment

* fix error message

Co-authored-by: zhouzaida <zhouzaida@163.com>

* [Fix] Fix ema state dict swapping in EMAHook.

* fix pt1.5 ut

* add more 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

* Add pyupgrade pre-commit hook

* fix ut

* remove comments

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

* add comments

* add mmddp

* update

* update code

* update unittest

* fix comment