[FSDP][state_dict] Expose optimizer state_dict config (#105949)
Optimizer state_dict config are not exposed. This PR exposes the 2 dataclass.
Differential Revision: [D47766024](https://our.internmc.facebook.com/intern/diff/D47766024/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/105949
Approved by: https://github.com/rohan-varma
