fish: remove fish-based nix-which

nix/homeModules/common/fish/functions/nix-which.fish

@@ -1,16 +0,0 @@
-function nix-which \
-    --description "List how an executable is linked in a NixOS system"
-
-    if [ (count $argv) -ne 1 ]
-        echo "Must provide exactly one argument, the package to be dereferenced"
-        return 1
-    end
-
-    set target (which "$argv[1]")
-    echo "==> $target"
-
-    while [ -L "$target" ]
-        set target (readlink "$target")
-        echo "==> $target"
-    end
-end