Added Node packages script

Necessary to provide a single source of truth for installing Node
dependencies. This used to be managed by the Yarn Setup project but
that project is being deprecated in favor of this project.

bin/install_node_packages

@@ -0,0 +1,17 @@
+#! /usr/bin/env bash
+
+# Installs Node packages.
+
+set -o nounset
+set -o errexit
+set -o pipefail
+IFS=$'\n\t'
+
+SCRIPT_PATH="$MAC_OS_CONFIG_PATH/bin/install_node_packages"
+
+if [[ -x "$SCRIPT_PATH" ]]; then
+  check_yarn_install
+  "$SCRIPT_PATH"
+else
+  printf "WARNING: Node packages install script does not exist or is not executable.\n"
+fi