[fx2trt] Add op converters for ads 23x dense arch
Summary:
Adding 4 converters for
1. torch.addmm
2. torch.mul
3. torch.t
4. torch.sigmoid
Test Plan:
fx2trt unittests
Able to lower dense arch with fx2trt locally.
Reviewed By: ajtulloch, yinghai
Differential Revision: D29563962
fbshipit-source-id: 114c4e871efb25379043224f5f0116829cd7dc50
