Add more tests for sizeAdd node. (#4258)
* add moore tests.
* Added more test for SizeAdd
* fix linter
* check EXPERIMENTAL flag in the test.
* check SizeAdd::ToString()
* resolved a few pr comments.
* fix typo.
* fix more pr comments
* make sizeAdd not to use s64.
* fix typo
* fix linter
* added a cpp test
* fix a comment.
* return s32 for GetShapeDimensionType
