refactor(@angular/cli): use ES6 imports instead of require

Main benefit is to use type definitions.

Author: alan-agius4

packages/angular/cli/BUILD.bazel

@@ -69,6 +69,7 @@ ts_library(
         "//packages/angular_devkit/core/node",
         "//packages/angular_devkit/schematics",
         "//packages/angular_devkit/schematics/tools",
+        "@npm//@angular/core",
         "@npm//@types/debug",
         "@npm//@types/inquirer",
         "@npm//@types/node",
@@ -79,6 +80,7 @@ ts_library(
         "@npm//@types/uuid",
         "@npm//ansi-colors",
         "@npm//jsonc-parser",
+        "@npm//open",
         "@npm//ora",
     ],
 )

packages/angular/cli/commands/doc-impl.ts

@@ -6,12 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import * as open from 'open';
 import { Command } from '../models/command';
 import { Arguments } from '../models/interface';
 import { Schema as DocCommandSchema } from './doc';
 
-const open = require('open');
-
 export class DocCommand extends Command<DocCommandSchema> {
   public async run(options: DocCommandSchema & Arguments) {
     if (!options.keyword) {
@@ -39,7 +38,7 @@ export class DocCommand extends Command<DocCommandSchema> {
       // and use it if we can find it
       try {
         /* tslint:disable-next-line:no-implicit-dependencies */
-        const currentNgVersion = require('@angular/core').VERSION.major;
+        const currentNgVersion = (await import('@angular/core')).VERSION.major;
         domain = `v${currentNgVersion}.angular.io`;
       } catch (e) { }
     }