add channels last for MaxPool2d (#48917)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48917
max_pool2d channels last support forward path
max_pool2d channels last support backward path
vectorize channels last forward path
rename the header file
fix windows build
combine PoolingKernel.h into Pool.h
add data type check
loosen test_max_pool2d_nhwc to cover device CPU
Test Plan: Imported from OSS
Reviewed By: glaringlee
Differential Revision: D25399470
Pulled By: VitalyFedyunin
fbshipit-source-id: b49b9581f1329a8c2b9c75bb10f12e2650e4c65a
