dbr quant: add test for qconfig_dict and methods (#70109)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70109
Adds a test case for DBR quant + qconfig_dict specifying methods
by object_type. Fixes a bug in the FX rewriter for scripting
to make the test pass.
Full coverage of methods will come in future PRs, this PR is
just to verify qconfig_dict is hooked up correctly.
Test Plan:
```
python test/test_quantization.py TestQuantizeDBR.test_qconfig_dict_object_type_method
```
Reviewed By: jerryzh168
Differential Revision: D33188160
Pulled By: vkuzo
fbshipit-source-id: 47ab9dbca8cdb1cf22d6d673d9c15b3bc0d1ec81
