[DataPipe] implementing demux() (#63650)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/63650
Test Plan: Imported from OSS
Reviewed By: ejguan
Differential Revision: D30493944
Pulled By: NivekT
fbshipit-source-id: 0aa06dee8c7fb1744975b8f6a0694b90c11ef80d
