* [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
Zaida Zhou