Just asegrep andfgrep have been deprecated by both the POSIX and GNU versions of grep, Debian has deprecated thergrep command it injects into the GNU grep package they distribute. (Which Ubuntu inherits, as well.)

The patches applied by Debian nowlist all three as deprecated (though all three are also listed as "Debian-specific", so perhapsegrep andfgrep have already been removed upstream?), even though it alsoremoves the deprecation warning fromegrep andfgrep (rgrep never had one).

This PR adds a new rule, SC2324, which is identical toSC2196 andSC2197 save that it targetsrgrep. As a bonus,rgrep has also been added to the list of greps for which-q should be suggested (SC2143).

It probably also makes sense to add all three variants toSC2126 (piping grep towc -l whengrep -c could be used instead), but I didn't discover that until I was typing up this description and my (fairly limited) Haskell skills aren't up to doing it quickly. 😅 If others agree that it should be done though, I'll happily make the change when I have more time in the next few days.