fix #45552 - adding add_done_callback(fn) to torch.futures.Future (#45675)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/45675
Test Plan: Imported from OSS
Reviewed By: glaringlee
Differential Revision: D24055353
Pulled By: bdhirsh
fbshipit-source-id: 9233c8e17acc878f0fecbe740a4397fb55cf722f
