Warn against constructors in callbacks without accepting scope as an argument

[dphfox]

In some areas of Fusion such as Computed callbacks, you're expected to place constructed items into a scope provided as an argument.

If the function is not defined with enough parameters, that scope is not accessible in the callback, and thus it's generally an error to construct objects in that callback as they'll pile up in another scope.

It's possible to detect this using the arity information from debug.info. When a 1-parameter callback is passed to a Computed, for example, we know that it will not capture the scope passed as argument 2, and as a result can infer that constructions inside that callback have no way to be cleaned up by the Computed. This is generally undesirable.

If for some reason the developer is explicitly logging to some other scope for later destruction, they can explicitly signal that the non-destruction of objects is intentional by including the scope parameter with an underscore prefix, explicitly showing that it is meant to be unused here.