ModuleNotFoundError: No module named 'torch.ao.quantization.experimental'
Labels: oncall: quantization, triaged

### 🐛 Describe the bug

Running 'pytest' gets these errors:
```
 ModuleNotFoundError: No module named 'torch.ao.quantization.experimental'
```

https://github.com/facebookresearch/d2go/issues/141

The code likely needs to be changed from:
```
from torch.ao.quantization.experimental.observer import APoTObserver
```
to:
```
from torch.quantization.experimental.observer import APoTObserver
```
in these file:
```
% grep torch.ao.quantization test/quantization/core/experimental/*.py
test/quantization/core/experimental/apot_fx_graph_mode_ptq.py:from torch.ao.quantization.experimental.quantization_helper import (
test/quantization/core/experimental/apot_fx_graph_mode_ptq.py:from torch.ao.quantization.experimental.qconfig import (
test/quantization/core/experimental/apot_fx_graph_mode_qat.py:from torch.ao.quantization.experimental.quantization_helper import (
test/quantization/core/experimental/test_fake_quantize.py:from torch.ao.quantization.experimental.observer import APoTObserver
test/quantization/core/experimental/test_fake_quantize.py:from torch.ao.quantization.experimental.quantizer import quantize_APoT, dequantize_APoT
test/quantization/core/experimental/test_fake_quantize.py:from torch.ao.quantization.experimental.fake_quantize import APoTFakeQuantize
test/quantization/core/experimental/test_fake_quantize.py:from torch.ao.quantization.experimental.fake_quantize_function import fake_quantize_function
test/quantization/core/experimental/test_linear.py:from torch.ao.quantization.experimental.linear import LinearAPoT
test/quantization/core/experimental/test_nonuniform_observer.py:from torch.ao.quantization.experimental.observer import APoTObserver
test/quantization/core/experimental/test_quantized_tensor.py:from torch.ao.quantization.experimental.observer import APoTObserver
test/quantization/core/experimental/test_quantized_tensor.py:from torch.ao.quantization.experimental.quantizer import quantize_APoT
test/quantization/core/experimental/test_quantizer.py:from torch.ao.quantization.observer import MinMaxObserver
test/quantization/core/experimental/test_quantizer.py:from torch.ao.quantization.experimental.observer import APoTObserver
test/quantization/core/experimental/test_quantizer.py:from torch.ao.quantization.experimental.quantizer import APoTQuantizer, quantize_APoT, dequantize_APoT
```

### Versions

```
% python collect_env.py 
Collecting environment information...
PyTorch version: N/A
Is debug build: N/A
CUDA used to build PyTorch: N/A
ROCM used to build PyTorch: N/A

OS: macOS 12.5.1 (x86_64)
GCC version: Could not collect
Clang version: 13.1.6 (clang-1316.0.21.2.5)
CMake version: version 3.22.1
Libc version: N/A

Python version: 3.10.4 (main, Mar 31 2022, 03:38:35) [Clang 12.0.0 ] (64-bit runtime)
Python platform: macOS-10.16-x86_64-i386-64bit
Is CUDA available: N/A
CUDA runtime version: Could not collect
GPU models and configuration: Could not collect
Nvidia driver version: Could not collect
cuDNN version: Could not collect
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: N/A

Versions of relevant libraries:
[pip3] mypy-extensions==0.4.3
[pip3] numpy==1.22.3
[pip3] torch==1.13.0a0+gitb2ddef2
[pip3] torchmetrics==0.9.3
[pip3] torchvision==0.14.0a0+a61e6ef
[conda] blas                      1.0                         mkl    anaconda
[conda] captum                    0.5.0                         0    pytorch
[conda] mkl                       2021.4.0           hecd8cb5_637    anaconda
[conda] mkl-service               2.4.0           py310hca72f7f_0    anaconda
[conda] mkl_fft                   1.3.1           py310hf879493_0    anaconda
[conda] mkl_random                1.2.2           py310hc081a56_0    anaconda
[conda] numpy                     1.22.3          py310hdcd3fac_0    anaconda
[conda] numpy-base                1.22.3          py310hfd2de13_0    anaconda
[conda] pytorch                   1.12.1                 py3.10_0    pytorch
[conda] torch                     1.13.0a0+git09157c7          pypi_0    pypi
[conda] torchmetrics              0.9.3              pyhd8ed1ab_0    conda-forge
[conda] torchvision               0.14.0a0+a61e6ef          pypi_0    pypi
(AI-Feynman) davidlaxer@x86_64-apple-darwin13 pytorch % 
```

cc @jerryzh168 @jianyuh @raghuramank100 @jamesr66a @vkuzo