* 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

Enabled eager_mode for complex unit tests, except for test_complex_op.py and test_complex_view_op.py (#40887)

* add support for complex grad accumulated

* add unittest for coverage

* update test dtype

* remove useless blank line