PreloadAllModules
提供一种预加载策略，以尽快预加载所有模块。
Provides a preloading strategy that preloads all modules as quickly as possible.
class PreloadAllModules implements PreloadingStrategy {
preload(route: Route, fn: () => Observable<any>): Observable<any>
}
说明
RouterModule.forRoot(ROUTES, {preloadingStrategy: PreloadAllModules})
