[DataPipe] Separating DataPipes from Dataset into different files (#73396)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73396
Separating DataPipes from Dataset into different files. This makes the code more maintainable and simplifies some of the code generation.
I have also tried to move `datapipe.py` into `torch.utils.data.datapipes`, but that will lead to circular import and rewriting many import statements. Should I put more time and go down that path some more?
Fixes https://github.com/pytorch/data/issues/213
Test Plan: Imported from OSS
Reviewed By: ejguan
Differential Revision: D34481962
Pulled By: NivekT
fbshipit-source-id: 42fb26fe7fc334636852cfd8719fc807bdaa7912
(cherry picked from commit 81e76a64e297cb5c58caa951c554e49526173936)
