[Quant] Add fused ConvAdd2d module for onednn backend (#91152)
**Summary**
Post op fusion can reduce data movement overhead and improve inference performance. This PR adds fused `ConvAdd2d` module for onednn backend, which will be used for int8 inference with onednn backend. Cannot call this module with other quantization backends otherwise an error is thrown.
**Test plan**
```
python -m pytest test_quantization.py -k test_conv2d_add
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91152
Approved by: https://github.com/jgong5, https://github.com/jerryzh168
