[DataPipe] Extend FileLister to support load multiple directories (#72260)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/72260
Test Plan: Imported from OSS
Reviewed By: dagitses, NivekT
Differential Revision: D33979744
Pulled By: ejguan
fbshipit-source-id: 5733d20382642fc2274afd838b33c98150d81e91
(cherry picked from commit f70537ae76448f5898da8d3f4884d0b3a29d40eb)
