Add test/test_namedtensor.py (#20168)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20168
ghimport-source-id: 78bd3c4b6bc87c216ce33dba13b61feb87e5fe53
Reviewed By: gchanan
Differential Revision: D15278222
Pulled By: zou3519
fbshipit-source-id: 3bcdb1cb654400350d42464dd9e0d5e0a7116e1e
