Add PTQ and exporting function
1. Add Post-Training Quantization
1.1 Abstract some functions from QAT to Quantization class
1.2 Add Post-Training Quantization by extending Quantization class
1.3 Add observers for PTQ
1.4 Add unittest for PTQ
2. Add exporting function for QAT and PTQ

* Add tools for quantization-aware training
1. Expose an API named paddle.quantization.QAT
2. Define a wrapper class to insert quanters into model for QAT
3. Add some functions in QuantConfig for QAT
4. Add unittest for QAT

* Add QuantedConv2D and QuantedLinear for QAT

* Add paddle.nn.quant.qat to setup.py

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* fix_docx_stanh

* fix einsum api en docs issue

* fix model api en docs issue

* for codestyle

* fix_einsum.py_einsum, test=document_fix

* fix_model.py_Model, test=ducument_fix

* fix_creation.py_meshgrid, test=document_fix

* fix_linalg.py_slogdet, test=document_fix

* fix_loss.py_SoftMarginLoss_CrossEntropyLoss_NLLLoss_BCELoss, test=document_fix

* norm.py_SyncBatchNorm, test=document-fix

* norm.py_SyncBatchNorm, test=document_fix

* norm.py_SyncBatchNorm, test=document_fix

* list18-30, test=document_fix

* refix_list1-15, test=document_fix

* deletefiles, test=document_fix

* fixedapi_pre-commit, test=document_fix

* fix_list31-45, test=document_fix

* list111, test=document_fix

* some_fix, test=document_fix

* some_fix, test=document_fix

* somefix, test=document_fix

* somefix, test=document_fix

* refix, test=document_fix

* refix, test=document_fix

* refix, test=document_fix

* refix, test=document_fix

* rerfix, test=document_fix
Co-authored-by: Ligoml <limengliu@tiaozhan.com>

* [CodeStyle][py2][U008] remove unnecessary args in `super()`

* remove remained args

* revert changes in test_pylayer_op

* Revert "revert changes in test_pylayer_op"

This reverts commit ff185a9ae738afac3b0264f61bde6c6b7f72e7c4.

* revert some changes in example code

* [CodeStyle][E712] use `if cond`/`if cond is True` for comparison with `True`

* revert changes in fluid

* revert unrelated file

* revert changes in norm

* revert changes in auto_parallel_amp

* fix norm and auto_parallel_amp

* revert a typo fix due to fixed at #47477

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

[CodeStyle][F401] remove unused imports in python_paddle/nn_tensor_reader_tests_distributed_distribution_dataset_utils. (#46721)

* 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

* cache core.ops, test=develop

* refine, test=develop

* Save all scales to target ops
* Move quant layers to paddle.nn.quant

* Add wrap for functional api
* Refine the wraped api
* Add unit test for quant functional layers
* Update all unit tests for dygraph qat