[BE Hackathon][DataPipe] Automatically generate datapipe.pyi via CMake (#73991)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73991
Automatically generate `datapipe.pyi` via CMake and removing the generated .pyi file from Git. Users should have the .pyi file locally after building for the first time.
I will also be adding an internal equivalent diff for buck.
Test Plan: Imported from OSS
Reviewed By: ejguan
Differential Revision: D34868001
Pulled By: NivekT
fbshipit-source-id: 448c92da659d6b4c5f686407d3723933c266c74f
(cherry picked from commit 306dbc5f469e63bc141dac57ef310e6f0e16d9cd)
