Support fp16 output in OnnxifiOp (#38846)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38846
We begin to have fp16 inputs/outputs. Adding this will help with the debugging.
Test Plan: run.
Reviewed By: jfix71
Differential Revision: D21676805
fbshipit-source-id: 47788e631164d24aef0f659b281c59822b009e18
