Add quick utility to transform scripted/traced models for mobile. (#35904)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35904
Currently this optimization means transform conv2d and linears to
prepacked(xnnpack) equivalent.
Test Plan: buck run fbsource//xplat/caffe2:optimize_for_mobile -- --model="/tmp/inpainting_fbnet.pt"
Reviewed By: AshkanAliabadi
Differential Revision: D20824433
fbshipit-source-id: 88d5c0d21b77911f95f018b03398b0df758ab0d7
