Refactor named tensor helper code (#22150)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22150
ghimport-source-id: 460022febc24f49b86f0d5dbf8dc227564bde6cb
Test Plan: Imported from OSS
Differential Revision: D15970325
Pulled By: zou3519
fbshipit-source-id: 86a3e3ca82bbf4ff815431e25c5f9a35fcd23be0
