feat(@schematics/angular): add type checking for protractor.conf.js file

Fixes #13958

Author: doggy8088

packages/schematics/angular/e2e/files/protractor.conf.js.template

@@ -1,8 +1,12 @@
+// @ts-check
 // Protractor configuration file, see link for more information
 // https://github.com/angular/protractor/blob/master/lib/config.ts
 
 const { SpecReporter } = require('jasmine-spec-reporter');
 
+/**
+ * @type { import("protractor").Config }
+ */
 exports.config = {
   allScriptsTimeout: 11000,
   specs: [