Import unused sample from a finished survey #2389
Description
In #2386 we discussed offering the ability to download the unused sample of a survey, so it can be reused in a new survey. We have done that some times in the past due to technical issues with the server or the channels that spoiled the survey results.
But, after some discussion, we found out this could potentially expose some info about the sample itself (for example, deanonimize which were the only two respondents that replied in a survey by downloading the unused sample, and diff'ing it with the original one). It would also open up the possibility of a collaborator that doesn't typically handle sample to get access to it.
Instead of that, the solution we've come up with is to provide an option in the survey creation UI to add the unused sample of another survey to the current one. This could work both for new or ongoing surveys.
Superseeds #2386