[ao][sparsity] Implemented state dict and serialization functionalities
The state of the data sparsifier object contains the name->mask mapping, name -> config mapping and the state_dict() of the container.
The load_state_dict() and __set_state__() automatically creates a container moduie and loads the named data internally without having the user to intervene.
Test Plan:
```python test/test_ao_sparsity.py TestBaseDataSparsifier```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79427
Approved by: https://github.com/z-a-f
