[Static Runtime] Implement aten::nonzero out variant (#64126)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/64126
Test Plan:
Confirm out variant is called:
```
> buck run //caffe2/benchmarks/static_runtime:static_runtime_cpptest -- --v=1
```
Reviewed By: mikeiovine
Differential Revision: D30617729
fbshipit-source-id: 752749638c8f467815efa57021cb3de5c728ab1b
