Add support for cat in output stitching (#66098)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66098
`cat` is somewhat special-cased right now because currently we only have list of Tensor inputs where the list is constructed in the JIT IR graph. While that is generally true for Fusion (e.g. why we have ConstantChunk) that may not be true for shape analysis generally, so I'm waiting a bit to generalize.
Test Plan: Imported from OSS
Reviewed By: navahgar, anjali411
Differential Revision: D31797467
Pulled By: eellison
fbshipit-source-id: ca761e214dfd7f3bba8d189f3b3f42ffec064f63
