Allow fuse unsqueeze cat sum with multiple input (#68650)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68650
Allow fuse unsqueeze cat sum with >2 input, the impl in this diff is naive, just concat item with add. Not sure can have more perf gain with fuse multiple add into one operation.
Test Plan: unit test
Reviewed By: jfix71
Differential Revision: D32520135
fbshipit-source-id: 535b1c8c91e415d5f1af714378b9205c1ca02ffd
