build(ngc): run integration test hermetically

This ensures we run in a clean directory, using our real distribution. It finds bugs like @internal
APIs needed to type-check in the offline compiler, as well as problems in package.json.

Also move tsc-wrapped under tools/@angular

modules/@angular/core/src/application_ref.ts

@@ -434,9 +434,6 @@ export const PLATFORM_CORE_PROVIDERS =
           /* @ts2dart_Provider */ {provide: PlatformRef, useExisting: PlatformRef_})
     ];
 
-/**
- * @internal
- */
 export const APPLICATION_CORE_PROVIDERS = /*@ts2dart_const*/[
   /* @ts2dart_Provider */ {provide: NgZone, useFactory: createNgZone, deps: []},
   ApplicationRef_,