Support serializing std::vector<torch::Tensor> (#19677)
Summary:
In the distributed training development work, we need to be able to serialize a `std::vector` of `torch::Tensor`s. This PR adds support for serializing `std::vector<torch::Tensor>`.
cc. mrshenli
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19677
Differential Revision: D15069860
Pulled By: yf225
fbshipit-source-id: 505147e5f5fea78be1bf60fb8418bc187dbc2a98
