Add l2 norm minimization (#24022)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24022
In histogram observer add an approximation for L2 error minimization for selecting min/max.
By selecting new min/max, we filter out outliers in input distribution.
This follows the implementation of NormMinimization::NonlinearQuantizationParamsSearch in caffe2/quantization/server/norm_minimization.cc
ghstack-source-id: 90298789
Test Plan: buck test mode/dev caffe2/test:quantization -- 'test_histogram_observer'
Differential Revision: D16713239
fbshipit-source-id: 82631ba47974e25689c9c66bc3088117090e26d4
