* [Refactor] Refactor fileio but without breaking bc

* handle compatibility

* fix format

* modify io functions

* fix ut

* fix ut

* rename method names

* refine

* refine docstring

* fix ut in windows

* update ut

* minor fix

* ensure client is not None when closing it

* add more examples for list_dir_or_file interface

* refine docstring

* refine deprecated info

* fix ut

* add a description for lmdb docstring

* [Refactor] Refactor the import rule

* minor refinement

* add a comment

* move fileio directory from utils

* remove CephBackend from fileio and clear some deprecated docstring

* fix format

* fix a spellling error

* tmp add fileio

* ignore fileio mypy check error