Missing cases for builtin Maybe descriptors in make_symbol_name

Function make_symbol_name in graph_copy_with_names needs some extra alternatives for the new descriptors for builtin Maybe types. I'm confused what these should look like. In _system.abc, _Just and _Justs both use the string ?Just. I think _Just should use ?^Just, so that they can be distinguished by make_symbol_name.

Also, make_symbol_name has an alternative for Cons?!, while [ !] in _system.abc is just Cons! (like [! ]).

Could you have a look at how this should be?