[DataPipe] Adding serialization test at different stages of reading for IterDataPipes (#73119)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73119
Test if a DataPipe is serializable after its contents are partially read and completely read. This is especially important for DataPipes with buffers.
Test Plan: Imported from OSS
Reviewed By: ejguan
Differential Revision: D34354496
Pulled By: NivekT
fbshipit-source-id: 36971d68b9ca1de81fb254e9a459b8f54fe0f9ff
(cherry picked from commit e8f39a7aa364bd2b19145788f7e67c06f948f81b)
