Support *args in Pipe.forward API. (#55441)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55441
This is the first step towards supporting the proposal outlined in
https://github.com/pytorch/pytorch/issues/53952.
In this PR I've ensured Pipe.forward() accepts a *inputs argument instead of
just a single input as previously. This lays the groundwork for supporting
non-Tensors and generic arguments to the Pipe API. In this PR we still only
support Tensors and non-Tensor support will come in future PRs.
For backward compatibility I've ensured a single Tuple[Tensor] input still
works as expected previously.
ghstack-source-id: 130767499
Test Plan: waitforbuildbot
Reviewed By: SciPioneer
Differential Revision: D27613887
fbshipit-source-id: 05e19e537e6d7fe4999745fc4ba9941ac54906de
