Add get_all_users_of function to GraphManipulation (#45216)
Summary:
This PR adds get_all_users_of function. The function returns all the users of a specific node. A test unit is also added.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45216
Reviewed By: ezyang
Differential Revision: D23883572
Pulled By: scottxu0730
fbshipit-source-id: 3eb68a411c3c6db39ed2506c9cb7bb7337520ee4
