Post_training_quantization support set quant 8/16 bits 

* Add weight quantization in post_training_quanzitaion (#22445)

* [cherry-pick]Support int16 for Tensor (#22423)

* add int16 support, test=develop, test=release/1.7
Co-authored-by: NLeo Chen <chenqiuliang@baidu.com>

* add mul and matmul quantization, test=develop (#22054)
* add test for matmul, test=develop

* fix post training quantization bug of memory constrained, support the input be different, test=develop

* support set model_filename and params_filename in post_training_quantization, test=develop

* Support  more ops in post training quantization, and save the output scale in quantized op.
* Update docs in post training quantization and qat 

* add post training quantization, test=develop
* specify the quantizable op type, test=develop