The $zip operator in classic is able to lazily evaluate the arguments passed to `default`, so that it avoids computing potentially expensive expressions.

But the initial implementation of $zip in SBE (see SERVER-51565) followed what is apparently the more used alternative in SBE, that of eagerly evaluating expressions so that they are ready to be dispatched to built-in functions.

So the idea here is to reimplement $zip in a way that 1) leverages even more the SBE functions and 2) lazily evaluates the `defaults` argument (there's a explanation of how this could work here).