build(zone.js): add changelog gulptask for zone.js (#31852)

PR Close #31852

tools/gulp-tasks/changelog-zonejs.js

@@ -0,0 +1,23 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+module.exports = (gulp) => () => {
+  const tag = process.env.ZONE_TAG;
+  const conventionalChangelog = require('gulp-conventional-changelog');
+  return gulp.src('packages/zone.js/CHANGELOG.md')
+      .pipe(conventionalChangelog(
+          {preset: 'angular'}, {
+            currentTag: tag,
+          },
+          {
+            // Ignore commits that have a different scope than `zone.js`.
+            extendedRegexp: true,
+            grep: '^[^(]+\\(zone\\.js\\)',
+          }))
+      .pipe(gulp.dest('./packages/zone.js/'));
+};