add BFloat16 support for fold and unfold on CPU (#62880)
Summary:
Add BFloat16 support for fold and unfold operators on CPU.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62880
Reviewed By: iramazanli
Differential Revision: D30576387
Pulled By: zou3519
fbshipit-source-id: c48f6e56702bfea34448db1b3a1634c49c5d8ec8
