[DML] Using DirectMLX.h can't set roundingType or outputSizes for pool2d

[mingmingtasd]

Failed to run Pool2d tests with outputSizes [4,4] or roundingType as ceil on DML.
These following six tests could run pass by native OpenVINO backend, while run fail by native DML backend

[  FAILED  ] Pool2dTests.MaxPool2dAutoPadExplicitOutputSizes4x4Nhwc
[  FAILED  ] Pool2dTests.MaxPool2dAutoPadExplicitRoundingTypeCeilNhwc
[  FAILED  ] Pool2dTests.AveragePool2dAutoPadExplicitOutputSizes4x4Nhwc
[  FAILED  ] Pool2dTests.AveragePool2dAutoPadExplicitRoundingTypeCeilNhwc
[  FAILED  ] Pool2dTests.l2Pool2dPadsOutputSizes4x4
[  FAILED  ] Pool2dTests.l2Pool2dPadsRoundingTypeCeil

Their output data are not as expected.

This issue would also make test them fail by Node binding for DML backend.

DirectML native API requires the output tensor shape which contains the outputSizes, it will not use roundingType as parameter since outputSizes can already predict the roundingType.
While using DirectMlX.h as the wrapper of DirectML native API, we can't set correct outputSizes which need to match the specified roundingType. Using DirectMlX.h will let pool2d perform as specifying floor roundingType.
Fixing this issue will depend on #172 to remove DirectMLX.h.

[mingmingtasd]

Also track in DirectML github: microsoft/DirectML#205