Demand Outputable syntax improvements: Call SubDemand

@simonpj said that he regularly gets confused about Demands with a Call SubDemand like 1C1(C1(L), where there's a Card before and after the C.

The correct association is 1 C1( C1(L) ), e.g., the first 1 is from the outer evaluation Demand while the second 1 describes how often the thing was called and therefore belongs to the Call SubDemand.

To make this more obvious and in line with Prod SubDemands, we agreed to put the Card inside the parens, too, e.g., 1C(1,C(1,L)).

This ticket is to track that change.