[state_dict][4/N] Support strict flag for model.load_state_dict (#111109)
As title
Differential Revision: [D50209723](https://our.internmc.facebook.com/intern/diff/D50209723/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111109
Approved by: https://github.com/wz337
ghstack dependencies: #111106, #111107, #111275
