[quant] quantized path for ConstantPadNd (#43304)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/43304
Test Plan: Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D23231946
Pulled By: z-a-f
fbshipit-source-id: 8c77f9a81f5a36c268467a190b5b954df0a8f5a4
