* refine and add test case

* support ellipsis type slice

* refine

* refine

* support slice assign ellipsis type

* refine

* register fn to localtensor

* basic implemetation of dataloader

* format

* refine as comments

* fix comments

* remove useless code

* add test case into unnitest

* refine ascomments

* refine as comments

* register uint8 dtypeto support dataloader

* add cifer mnist dataset support

* format

* refine

* refine

* use F.interpolation

* export dataloader dataset

* export more api

* refine

* refine

* add oneflow_test_cache_dir

* refien

* refine

* refine

* refine

* update datasets links

* refine

* fix comment

* unset export

* auto format by CI

* add requirement

* always reisntall test deps

* update requirement

* add pillow as oneflow dependency

* auto format by CI

* add sessiong context debug str

* remove debug str

* remove experimental

* fix export

* update

* fixbug

* auto format by CI

* refine

* refine

Co-authored-by: oneflow-ci-bot <69100618+oneflow-ci-bot@users.noreply.github.com>
Co-authored-by: tsai <jackalcooper@gmail.com>
Co-authored-by: oneflow-ci-bot <ci-bot@oneflow.org>