Lower count_nonzero (#5137)
* added count_nonzero node
* first test passed.
* fix a test.
* compiles
* fixed the test without dim
* python test seems work.
* made the list case work
* ran linter
* rebased
* resolved conflicts
* ran linter
* remove unwantted change
* remove unwanted change
* remove unwanted change
* fix build error
* fix comments
* fix comments
* fix unwanted
* fix comment
