* move DataLoader to paddle.io. test=develop

* fix some docs bugs; test=document_fix

* Update batch_sampler.py

* Update dataset.py

* Update dataset.py

* Update sampler.py

* for codestyle; test=document_fix

* fix copy-from issue; test=document_fix
Co-authored-by: NLigoml <39876205+Ligoml@users.noreply.github.com>
Co-authored-by: Ligoml <limengliu@tiaozhan.com>

* [CodeStyle][py2][U004] unecessary explicit `object` inheritance in class definition

* fix an increment

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* trim trailing whitespace

* fix `.cmake-format.py`

* revert npu ut changes, avoid npu ci error

* 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

* add WeightedRandomSampler. test=develop

* fix RandomSampler & BatchSampler. test=develop

* add Sampler/SequenceSampler/RandomSampler. test=develop