build: add check yarn preinstall script

Direct copy of the script from core.

Author: clydin

package.json

@@ -34,6 +34,7 @@
     "validate": "node ./bin/devkit-admin validate",
     "validate-commits": "./bin/devkit-admin validate-commits",
     "prepush": "node ./bin/devkit-admin hooks/pre-push",
+    "preinstall": "node ./tools/yarn/check-yarn.js",
     "webdriver-update-appveyor": "webdriver-manager update --standalone false --gecko false --versions.chrome 2.37",
     "webdriver-update-circleci": "webdriver-manager update --standalone false --gecko false --versions.chrome $CHROMEDRIVER_VERSION_ARG "
   },

tools/yarn/check-yarn.js

@@ -0,0 +1,14 @@
+/**
+ * @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
+ */
+
+'use strict';
+
+if (process.env.npm_execpath.indexOf('yarn') === -1) {
+  throw new Error(
+      'Please use Yarn instead of NPM to install dependencies. See: https://yarnpkg.com/lang/en/docs/install/');
+}