quantized add: enable broadcasting (#66049)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66049
Enables quantized add with broadcasting. As pointed out by jamesr66a,
this was disabled but TensorIterator already supports it. Added a test
case to verify.
Test Plan:
```
python test/test_quantization.py TestQuantizedOps.test_qadd_broadcast
```
Imported from OSS
Reviewed By: dagitses
Differential Revision: D31472850
fbshipit-source-id: a3b16d9000487918db743525d22db6864330762b
