* Fix albu BUG: using albu will cause the label from array(x) to array([x]) and crash the trainning
* Fix common
* Using copy incase potential bug in multi-label tasks
* Improve coding
* Improve code logic
* Add unit test
* Fix typo
* Fix yapf
* refactor resize, test tobe done
* resize reimpl according to discussion; add pad
* minor fixes and add tests
* minor fixes on docstring
* add additional unit test
* reformat resize and pad
* revise code and docstr according to the comments
* Refactor unit tests folder structure.
* Remove label smooth and Vit test in `test_classifiers.py`
* Rename test_utils in dataset to test_dataset_utils
* Split test_models/test_utils/test_utils.py to multiple sub files.
* Add unit tests of classifiers and heads
* Use patch context manager.
* Add unit test of `is_tracing`, and add warning in `is_tracing` if torch
verison is smaller than 1.6.0