Allow converting IValue to vector<string> (#34269)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34269
follow up for https://github.com/pytorch/pytorch/pull/16519
Test Plan: unit tests
Reviewed By: houseroad
Differential Revision: D20261495
fbshipit-source-id: 947f3cbd469d9258ec2dbb36cb68efe15a3b19eb
