Add -ss flag to stop at first successful response (#571)

[xbol0]

Description

Added -ss flag to stop at first successful response.

I think that it should be conflict to other stop flags. So I made it throw a warning message when user provided them.

Fixes: #571

Additonally

• If this is the first time you are contributing to ffuf, add your name to CONTRIBUTORS.md.
  The file should be alphabetically ordered.
• Add a short description of the fix to CHANGELOG.md

Thanks for contributing to ffuf :)

[joohoi]

Thanks for the PR, and sorry it took so long to get around to review it.

I do like the idea for the flag, but I would argue that we should modify the behavior a bit from this initial suggestion. If I'm not mistaken the potential use case example for this is to fuzz things like credentials and such, and for that I believe we should abstract the definition of success a bit. So how about changing the behavior to stop on first match instead of hardcoded status codes etc?