fix(build): build/test on windows (#6431)

* build: build/test on windows

* chore(deps): bump @hyperjump/json-schema from 0.18.4 to 0.18.5
* chore(deps): add gulp-gzip 1.4.2
* build: migrate test scripts to gulp task (test_tasks.js)
* build: not to use the grep command
* build: normalize path

* fix: Modified based on review suggestions.
* Add JSDoc comment
* Line length <= 80 characters.
* Formatting test output as previously.
* Always continue even if a test unit fails.
* Suppress the gulp messages.
* Fix test_tasks.js to pass eslint.

* fix: Modified based on review suggestions.
* Change generator test output directory.
* Formatting test output as previously.

* fix: Formatting test output as previously.

* fix: Modified based on review suggestions.

scripts/helpers.js

@@ -0,0 +1,35 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Helper functions for build/test.
+ */
+/* eslint-env node */
+
+const path = require('path');
+
+/**
+ * Escape regular expression pattern
+ * @param {string} pattern regular expression pattern
+ * @return {string} escaped regular expression pattern
+ */
+function escapeRegex(pattern) {
+  return pattern.replace(/[-/\\^$*+?.()|[\]{}]/g, '\\$&');
+}
+
+/**
+ * Replaces OS-specific path with POSIX style path.
+ * @param {string} target target path
+ * @return {string} posix path
+ */
+function posixPath(target) {
+  const osSpecificSep = new RegExp(escapeRegex(path.sep), 'g');
+  return target.replace(osSpecificSep, path.posix.sep);
+}
+
+module.exports = {
+  posixPath,
+};