* support print using hooks before running.
* Support to print hook trigger stages.
* Print stage-wise hook infos. And make `stages` as class attribute of
`Hook`
* Add util function `is_method_overriden` and use it in
`Hook.get_trigger_stages`.
* Add unit tests.
* Move `is_method_overriden` to `mmcv/utils/misc.py`
* Improve hook info text.
* Add base_class argument type assertion, and fix some typos.
* Remove `get_trigger_stages` to `get_triggered_stages`
* Use f-string.
Jerry Jiarui XU
Ma Zerun
Junjun2016
Kai Chen