[Quant][test] Add test for mixed dtypes in the same model (#96104)
Summary: This commit adds a test for mixing multiple dtypes
for different layers in the same model. The test verifies that
FX graph mode quantization converts the dtypes correctly
between the layers.
Test Plan:
python test/test_quantization.py TestQuantizeFx.test_mixed_dtypes
Reviewers: jcaip, vkuzo, supriyar
Subscribers: jcaip, vkuzo, supriyar
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96104
Approved by: https://github.com/jcaip
