[quant] Make version 1 the default for get_default_qat_qconfig (#63043)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63043
In version 1 we use the fused module/operator during QAT. Making this the default for all QAT runs going forward.
Older models saved after prepare_qat_fx can still load their state_dict into a model prepared using version 1.
The state_dict will still have the same attribute for the observer/fake_quant modules.
There may be some numerics difference between the old observer code in observer.py and the new fused module that was
re-written in C++/CUDA to perform observe + fake_quantize.
This PR also updates the test to check for the new module instead of the default FakeQuantize module.
Note: there are also some changes to make the operator work for multi-dim per-channel quantization + updated the test for that.
Test Plan:
python test/test_quantization.py TestSerialization.test_default_qat_qconfig
Imported from OSS
Reviewed By: raghuramank100
Differential Revision: D30232222
fbshipit-source-id: f3553a1926ab7c663bbeed6d574e30a7e90dfb5b
