* Fix ema hook and add unit test

* save state_dict of ema.module

save state_dict of ema.module

* replace warning.warn with MMLogger.warn

* fix as comment

* fix bug

* fix bug

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

* fix pt1.5 ut

* add more comments

* [Enhance] Add RuntimeInfoHook to update runtime information.

* move lr to runtime info

* docstring

* resolve comments

* update ut and doc

* [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