Add support of count_include_pad and test end to end test for AveragePool (#17034)

Add support of count_include_pad and test end to end test for AveragePool (#17034)

Summary:
Add support of count_include_pad end to end test for AveragePool

We can export AveragePool from PyTorch with count_include_pad attribute. However, we don't directly support it in Caffe2's ONNX backend.
We also want to check whether we can pass the end to end test for average pool operator with count_include_pad attribute (pytorch => onnx => caffe2)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17034

Reviewed By: houseroad

Differential Revision: D14060186

Pulled By: dwarakrajagopal

fbshipit-source-id: 10dae532611c71f8c8cfc3fa701cc7c1c1c02695