`group_size` hardcoded in `_infer_fake_quantize_configs`.

[salmanmohammadi]

Hi - I noticed today that group_size has been hardcoded to 128 here for Int4WeightOnlyConfig. Is this intentional?

[jerryzh168]

cc @andrewor14

[andrewor14]

I think it was to match the fbgemm kernel, but we can make it configurable