fix(bash-v2): activeHelp length check syntax (#1762)

```shell
$ set -u
$ foo=()
$ echo ${#foo}
bash: foo: unbound variable
echo ${#foo[*]}
0
```
The above shows that an empty array needs the suffix `[*]` when checking its length, or else it is considered unbound.

bash_completionsV2.go

@@ -150,7 +150,7 @@ __%[1]s_process_completion_results() {
     __%[1]s_handle_special_char "$cur" =
 
     # Print the activeHelp statements before we finish
-    if [ ${#activeHelp} -ne 0 ]; then
+    if [ ${#activeHelp[*]} -ne 0 ]; then
         printf "\n";
         printf "%%s\n" "${activeHelp[@]}"
         printf "\n"