Support z -- dir for zsh and fish (#858)

templates/fish.txt

@@ -82,6 +82,8 @@ function __zoxide_z
         __zoxide_cd -
     else if test $argc -eq 1 -a -d $argv[1]
         __zoxide_cd $argv[1]
+    else if test $argc -eq 2 -a $argv[1] = --
+        __zoxide_cd -- $argv[2]
     else if set -l result (string replace --regex -- $__zoxide_z_prefix_regex '' $argv[-1]); and test -n $result
         __zoxide_cd $result
     else

templates/zsh.txt

@@ -59,6 +59,8 @@ function __zoxide_z() {
         __zoxide_cd ~
     elif [[ "$#" -eq 1 ]] && { [[ -d "$1" ]] || [[ "$1" = '-' ]] || [[ "$1" =~ ^[-+][0-9]$ ]]; }; then
         __zoxide_cd "$1"
+    elif [[ "$#" -eq 2 ]] && [[ "$1" = "--" ]]; then
+        __zoxide_cd "$2"
     else
         \builtin local result
         # shellcheck disable=SC2312