* move fluid.utils to paddle.utils.layers_utils

* fix error

* delete original fluid layers utils

* remove import and old utils

* remove more old utils import

* change import path of fill_constant in the layers_utils.py

* fix mistake

* fix error

* expose in __init__.py

* for comment

* when change the ref of func is_sequence, it should change to the root of is_sequence instead

* for codecheck

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* standard api

* fix sparse bugs

* fix xpu bugs, test=kunlun

* remove hard code for custom unittest

* open ci, test=kunlun

* deal with conflict

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format