* 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

* 1. add the python api grad 2. add final and intermediate state vlog 3. change the python_api error logic

* add python api or close the check_eager=True

* fix the compatibility

* run pre-commit

* use HOST or DEVICE instead of HOSTDEVICE in implementation of lgamma op

* add test for fp32

* add lgamma to op_threshold_white_list

* add cuda kernel for lgamma kernel

* modify numeric grad delta

* fix small English issue

* change LaunchElementwiseCudaKernel to LaunchSameDimsElementwiseCudaKernel