Add fish module to nix

archive/fish/functions/ensure_path.fish

@@ -1,7 +0,0 @@
-function ensure_path --description "Ensures directories are in $PATH"
-    for pathdir in $argv
-        if not set -l index (contains -i $pathdir $PATH)
-            set -g -x PATH $pathdir $PATH
-        end
-    end
-end