pytorch

a689e3a0 - Support per channel quantization in insert_quant_dequant and fold_prepack (#29492)

Support per channel quantization in insert_quant_dequant and fold_prepack (#29492) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/29492 Previously graph mode quantization only works for per tensor quantization, this PR added support for per channel quantization as well, changes include - insert per channel quantization calls(insert_quant_dequant) - add support of folding for prepacked per channel quantized weight (fold_prepack) Test Plan: test is not possible until we can script PerChannelObserver, which comes in https://github.com/pytorch/pytorch/pull/29416 we'll add test in a separate PR after that. Imported from OSS Differential Revision: D18580444 fbshipit-source-id: 347c07f201648ec49f070523642a9170278f8aa4