Fix tracing for modules with List[Tensor] as output (#31343)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31343
Fix an issue in TorchScript tracing for modules with `c10::List<at::Tensor>` as an output. TensorList was not supported properly.
Test Plan: unit tests
Reviewed By: wanchaol
Differential Revision: D18850722
fbshipit-source-id: 87a223104d1361fe754d55deceeb1e8bbcad629b
