optimize a bert model converted using tf2onnx (#5492)
* optimize a bert model converted using tf2onnx
* add test data
* update
* remove comments
* format
* Revert "format"
This reverts commit f8ae88cb564bce5caf4780e56561403f3ba3d524.
* Revert "remove comments"
This reverts commit 59d8a693581a731fd0291b70fe2c9cec6c4950fe.
* add a squeeze node to convert a 3-d mask to 2-d
* update
* update
* verify and add comments
