Make fusion strategy api public (#72639)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/72639
Test Plan: Imported from OSS
Reviewed By: soulitzer
Differential Revision: D34159123
Pulled By: eellison
fbshipit-source-id: 27e4d9694a83e8d6829009882715be4308c96a9f
(cherry picked from commit 1cadcd2f756ae3b52bcc5c60ff266dd950acfc56)
