[fx] Add a function to allow adding more functions to the side effect function set (#97288)
Summary: There're some customized functions that we would also like to keep during eliminate dead code pass. Add a function to help us to do.
Test Plan: Added a unit test
Differential Revision: D44273630
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97288
Approved by: https://github.com/houseroad
