[quant][graphmode][fx] Add support for single linear and conv2d (#66950)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66950
Just to show that it works for weighted operations as well, qat/fused op not supported yet
We can start developing the backend_config_dict and work towards making the support more complete afterwards
Test Plan: Imported from OSS
Reviewed By: vkuzo
Differential Revision: D31801782
fbshipit-source-id: 8491bab7939a7a1c23ffa87c351844b82e390027
