* Add cosine cool down lr updater
* Use ema hook
* Update decay mult
* Update configs.
* Update T2T-ViT readme and format all readme
* Update swin readme
* Update tnt readme
* Add docstring for `CosineAnnealingCooldownLrUpdaterHook`.
* Update t2t readme and metafile
* Added NumClassCheckHook and CI tests
* Added HOOKS local registry. NumClassCheckHook and unit test files redistribution.
* Extended hook for supporting IterRunner & EpochRunner. Extended unit test.
* Simplification of ClassNumCheckHook. Minor changes.