dbr quant: refactor `get_quantized_op` to only use `seen_op_info` (#68342)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68342
Before this PR, `get_quantized_op` required the current callable.
After this PR, `get_quantized_op` only requires `seen_op_info`.
The signature was changed slightly to return `None` if the original
callable does not need replacement for quantization.
This will make it easier to make performance improvements in a
future PR.
Test Plan:
```
python test/test_quantization.py TestQuantizeDBR
```
Reviewed By: jerryzh168
Differential Revision: D32463768
Pulled By: vkuzo
fbshipit-source-id: 5db2c4199f6c0529817f4c058f81fd1d32b9fa9f
