Added foreach_frac API (#47384)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47384
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D24737052
Pulled By: izdeby
fbshipit-source-id: 8c94cc42bf22bfbb8f78bfeb2017a5756045763a
