angular-cli built-in package 作用

使用angular cli 创建的项目，默认的依赖如下：

"dependencies": {
    "@angular/animations": "~10.1.3",
    "@angular/common": "~10.1.3",   // httpClient； ngClass, ngForOf 等内置指令；DatePipe， JsonPipe 等内置pipe; 等等...
    "@angular/compiler": "~10.1.3",
    "@angular/core": "~10.1.3",   // 基于rxjs的Subject 的EventEmitter 事件发射机制, ErrorHandler基类; change detection 相关逻辑; angular zone；等等...
    "@angular/forms": "~10.1.3",
    "@angular/platform-browser": "~10.1.3",  //封装了浏览器基本的service
    "@angular/platform-browser-dynamic": "~10.1.3", // 使用浏览器core 实例化启动当前APP
    "@angular/router": "~10.1.3",   // router 相关的指令；route 相关的事件钩子；router 状态维护；等等...
    "rxjs": "~6.6.0",    // 响应式变成库，观察者模式
    "tslib": "^2.0.0",   // typescript helper library
    "zone.js": "~0.10.3"  // 异步任务完成后，主动调用变更检测；拦截浏览器原生API; 等等...
  },
"devDependencies": {
    "@angular-devkit/build-angular": "~0.1001.3",
    "@angular/cli": "~10.1.3",
    "@angular/compiler-cli": "~10.1.3",
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "^12.11.1",
    "codelyzer": "^6.0.0",
    "jasmine-core": "~3.6.0",
    "jasmine-marbles": "~0.6.0",
    "jasmine-spec-reporter": "~5.0.0",
    "karma": "~5.0.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~3.0.2",
    "karma-jasmine": "~4.0.0",
    "karma-jasmine-html-reporter": "^1.5.0",
    "protractor": "~7.0.0",
    "ts-node": "~8.3.0",
    "tslint": "~6.1.0",
    "typescript": "~4.0.3"
  }