Use Int8QuantParamsBlob to pass the scale and zeropoint params (#40390)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40390
Change the Int8FC/Int8Quantize op interface to use Int8QuantParamsBlob as the qparam input blob format when needed.
Test Plan:
```
buck test caffe2/caffe2/quantization/server:
```
Reviewed By: hx89
Differential Revision: D22124313
fbshipit-source-id: 6b5c1974c0fc5928f72773495f0da8d0eb9b98c9