[JIT] Make torch.unique_consecutive compatible (#39339)
Summary:
A `unique_consecutive` version of https://github.com/pytorch/pytorch/pull/38156
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39339
Differential Revision: D21823997
Pulled By: eellison
fbshipit-source-id: d14596a36ba36497e296da5a344e0376cef56f1b
