* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* Support append method and initialized value for List in ControlFlow

* polish error msg and en doc

* fix code style

add __all__=[] to python files not in API public list; import * only support in API public list files (#32643)

4 APIs: array_length, array_read, array_write, create_array