Make ::jsstack output JSFunction instances by default

[misterdjules]

This came out originally from #54, which was about solving some UX issues that users encountered when trying to find the appropriate address to use as input for the ::jsclosure command.

#55 improved the documentation, but per @davepacheco's comments:

We used to print the JSFunction in ::jsstack, but I removed it from the default output because there was nothing useful you could do with it. Now that you can do useful things with it, we should probably add it back. That may help.

So we could probably display JSFunction instances by default to make using ::jsclosure easier. The documentation would need to be updated to.