Add script to run UMD tests

scripts/test_umd.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# This script runs umd tests and cleans up after them while preserving the `return_code` for CI
+# UMD tests should be only run after the commonjs build cause they reuse some of the commonjs build artefacts
+run-s substitute_umd_bundle run_mocha
+return_code=$?
+npm run clean
+exit $return_code