* 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