[FSDP] Consolidate FSDP state_dict offload_to_cpu settings (#86211)
Consolidate FSDP state_dict offload_to_cpu settings. All state_dict_types now
have offload_to_cpu options.
Differential Revision: [D40065969](https://our.internmc.facebook.com/intern/diff/D40065969/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86211
Approved by: https://github.com/rohan-varma
