Fix trt tuple(Dims) throwing issue (#68318)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68318
Adding a `__iter__` binding so that when we do `tuple(Dims)` can construct the right iterator and knows where to stop instead of trial and error with exception catch. We should upstream this to https://github.com/NVIDIA/TensorRT. cc: wushirong
I did try a very similar `__iter__` fix previsouly but not sure why it wasn't effective...
Reviewed By: kflu, wushirong
Differential Revision: D32412430
fbshipit-source-id: 6390a1275dc34ef498acf933bb96f636c15baf41
