[quant][tensorrt] Add tensorrt backend config (#64623)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64623
The config api will change, but we'll add configs gradually for TensorRT to unblock experimentation
Test Plan:
python torch/fx/experimental/fx2trt/example/unittests.py
Imported from OSS
Reviewed By: vkuzo
Differential Revision: D30800474
fbshipit-source-id: 3c4640de1205a0f19b62943ab84f386d80394ec2
