Add stackoverflow parameter to debug.warning

[blernermhc]

It should behave similarly to what happens with debug.error.

[fong22e]

When querying StackOverflow in debug.error, the user is prompted to pass in a number from 1-6 to open the web page corresponding to the title of the page until they enter q when control exits the loop. This works right now because when provenance is collected using rdtLite, there can be only 1 error per script.

However, debug.warning allows the user to query multiple warnings at the same time. How should the function prompt the user for input? In terms of implementation, the easiest way would be to have 1 user input loop for each warning, run in sequential order. So the user would select pages for the first warning, input q to exit, then the user would be prompted to select pages for the second warning and so forth. In this case however, what if the user wishes to abort querying StackOverflow altogether? Let's say the user queries 3 warnings, but does not wish to continue querying StackOverflow after the first warning. What should happen then?