Make node.sh honor -i, if given, for validators

This is required for staked nodes for now, and is be superseded by
-staking=true option in harmony binary itself.

scripts/node.sh

@@ -653,6 +653,15 @@ do
    fi
 # backward compatible with older harmony node software
    case "${node_type}" in
+   validator)
+      case "${shard_id}" in
+      ?*)
+	 args+=(
+	    -shard_id="${shard_id}"
+	 )
+	 ;;
+      esac
+      ;;
    explorer)
       args+=(
       -node_type="${node_type}"