* saving inference model for user defined quantization model

* saving inference model for user defined quantization model

* fixed ci coverage

test=develop

* Add the imperative quantization aware training.
*  This is the python part of Imperative QAT. test=develop

test=develop

test=develop

* add user defined func test=develop

* update test=develop

* update test=develop

* fix name conflicts test=develop

* add unittest test=develop

* change 2018 to 2020 test=develop

* add comment test=develop

* add comment for function test=develop

* fix details test=develop

* fix details test=develop

* Post_training_quantization supports optimize model by fusing, test=develop

Update DNNL QAT document 2.0-alpha

[Fix bug] Init scale node in OutScaleForTrainingPass and enable test_quantization_scale_pass UT (#24393)

* Init scale node in OutScaleForTrainingPass, test=develop
* Enable test_quantization_scale, test=develop

* Enabled quantize all and skip missing in QAT

* update local data preprocess doc

* update for 2.0 QAT

test=develop

test=document_fix

* update benchmark data

test=develop

test=document_fix
Co-authored-by: NWojciech Uss <wojciech.uss@intel.com>

* QAT: support range-based quantization and scales from attribute

* added support for channelwise

* Weight quantization support channel_wise_abs_max method to achieve higher accuracy

* Update for QAT INT8 MKL-DNN document, added info on VNNI in Windows, benchmark results added and updated

* Collect output scale for quantized op and fused op
* Post_training_quantizaion sets batch_generator to support lod tensor

* Post_training_quantizaion supports min_max methon

* Added an option to use external FP32 model in QAT comparison test

* Doc update with Ernie QAT INT8 benchmarking

test=develop

* fixes after review

test=develop

* remove ernie part, test=develop test=document_fix

* Fix model name for qatv2

test=develop test=document_fix

* Add Ernie data

test=develop test=document_fix

* update ERNIE benchmark with baidu QA results, test=develop test=document_fix
Co-authored-by: Nbingyanghuang <33643817+bingyanghuang@users.noreply.github.com>
Co-authored-by: NMichał Gallus <sand3r@interia.eu>

* a test for Ernie QAT INT8 accuracy check

test=develop

* Remove NLP comparison test to split PRs

test=develop

* Fix typo and tabs, delete commented lines

test=develop

* re-combine the 2 PRs, test=develop
Co-authored-by: NMichał Gallus <sand3r@interia.eu>
Co-authored-by: Nbingyanghuang <33643817+bingyanghuang@users.noreply.github.com>

* post_training_quantization support set bits, test=develop

* up, test=develop

* support weight quantization in post_training_quanzitaion, test=develop
* add test for weight quantization, test=develop