enable support for nested containers in `torch.testing.assert(equal|close)` (#57270)
Summary:
In contrast to the initial opinion in https://github.com/pytorch/pytorch/issues/55385, there are legitimate use cases for nested containers. One such example is the [output of `LSTM`'s](https://pytorch.org/docs/stable/generated/torch.nn.LSTM):
```python
output: Tuple[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]] = torch.nn.LSTM()(input)
assert_close(output, expected)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57270
Reviewed By: albanD
Differential Revision: D28249303
Pulled By: mruberry
fbshipit-source-id: 75caa4414cc184ff0ce4cfc0dd5aafddfad42bcf
