Create test for validating shape-inference methods handle unknown rank inputs

[gramalingam]

See PR #6080 for context: it is an example of a shape-inference method that does not handle the case of inputs of unknown ranks gracefully (well, it crashes :-) ).

We should have a test (in CI) that validates that the shape-inference method of all operators handle inputs of unknown ranks without crashing. We just need to create a test-case where the input tensors do not have any shape (rank). One way to do this is to leverage existing test-cases (eg., from backend node tests) and modify the input type to have no shape, and run the shape-inference method on it.