* add defaut scope
* Fix docstring
* override get_current_instance method in DefaultScope
clean meta nameing
* remove default mmengine argument of DefaltScope
remove default mmengine argument of DefaltScope
remove default mmengine argument of DefaltScope
* Fix unit test
Fix unit test
* Fix example in docstring
* add explaination of DefaultScope
* Add the unittest of registry
* improve the format
* fix the test_repr
* refactor the test_init
* add the copyright for tests directory
* add more unit tests
* fix error
* add unit tests for _search_child and _get_root_registry
* build_from_cfg supports dict, ConfictDict and Config
* improve docstring