Add ability clone an eventing function

Feedback from Perry

Rather than have to manually create a new function (and get all of the bindings correct), and then copy-paste code from another function into it (and perhaps miss some interdependencies)...it would be very helpful to be able to clone an entire function right within eventing. And then, I would want to be able to either run a subset of the function, run it only on a single document, debug it without deploying, etc.