replicate state_dict tests (#90868)
Simple tests for replicate() state_dict. Ensuring composition with
FSDP works will come as a follow up.
Differential Revision: [D42048131](https://our.internmc.facebook.com/intern/diff/D42048131/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/90868
Approved by: https://github.com/awgu
