[quant][graphmode][fx] Add support for layer_norm (#43376)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43376
Porting op tests from test_quantize_jit.py
Test Plan:
TestQuantizeFxOps
Imported from OSS
Reviewed By: z-a-f
Differential Revision: D23257048
fbshipit-source-id: 47a04a5221bcaf930d574f879d515e3dff2d1f6d
