[ao][sparsity] Data Sparsity with Post Training Quantization (#82759)
Implementation of `post_training_sparse_quantize` that takes in a model
and applies sparsification and quantization to only `embeddings` & `embeddingbags`.
The quantization step can happen before or after sparsification depending on the `sparsify_first` argument.
Test Plan:
```python test/test_ao_sparsity.py TestQuantizationUtils```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82759
Approved by: https://github.com/z-a-f
