refactor(compiler): remove old ngtools api and add listLazyRoutes to new api (#19836)

Usages of `NgTools_InternalApi_NG_2` from `@angular/compiler-cli` will now
throw an error.

Adds `listLazyRoutes` to `@angular/compiler-cli/ngtools2.ts` for getting
the lazy routes of a `ng.Program`.
PR Close #19836

packages/compiler/src/core.ts

@@ -260,3 +260,8 @@ function makeMetadataFactory<T>(name: string, props?: (...args: any[]) => T): Me
   factory.ngMetadataName = name;
   return factory;
 }
+
+export interface Route {
+  children?: Route[];
+  loadChildren?: string|Type|any;
+}