SuperNode should become two nodes

[enebo]

Semantically super and super() are different semantically. It also feels awkward to check whether there is an opening token to know which one it is. Adding ZSuperNode wil not only not have tokens for parens it will also not have any arguments or a block.

[enebo]

This is needed for #807

[enebo]

ForwardingSuperNode already exists for ZSuper. This is not an issue.

[eregon]

Aside: it'd be pretty cool if YARP could desugar a zsuper into a regular super for execution purposes, i.e. desugar def m(a, b); a *= 2; super; end into def m(a, b); a *= 2; super(a, b); end.
IIRC that's the correct semantics for zsuper.
That would save Ruby implementations to have to do it themselves which is quite messy (IMO).

It'd a bit tricky if some arguments are unnamed, but those could probably still be encoded in some way (e.g. * could be named *, simply).

Not sure if this would be easy to do in YARP though.