torbrowser: fix argument handling in wrapper

With $@ unquoted, the wrapper would always just pass "" to firefox

(cherry picked from commit 4741627bcf60e9b16cd767a8d3ded6bcbf3691b2)

pkgs/tools/security/tor/torbrowser.nix

···
         ~/Data/Browser/profile.default/preferences/extension-overrides.js
     fi
     export LD_LIBRARY_PATH=${ldLibraryPath}:$out/share/tor-browser/Browser/TorBrowser/Tor
-    $out/share/tor-browser/Browser/firefox -no-remote -profile ~/Data/Browser/profile.default "$@"
+    $out/share/tor-browser/Browser/firefox -no-remote -profile ~/Data/Browser/profile.default "\$@"
     EOF
     chmod +x $out/bin/tor-browser