Write a Fortran test involving arrays-of-pointers state

This would involve modifying test_rk_codegen_fancy to use array-of-pointers state. On the Python end, all that needs changing is inserting a layer of PointerType in the type declaration. Ideally, that should generate, with most of the Python test unmodified, generate Fortran code to work on that data structure.

The main part of this bug beyond that would be writing an F90 driver to actually run the test.