Rename tensor.is_named to has_named, expose has_named to python.
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/23315
Test Plan:
- [namedtensor ci]
gh-metadata: pytorch pytorch 23315 gh/zou3519/79/head
Imported from OSS
Differential Revision: D16494414
Pulled By: zou3519
fbshipit-source-id: d2d6beb45db9288e5df707b68b6046d783ca9f97
