refactor(core): change module semantics

This contains major changes to the compiler, bootstrap of the platforms
and test environment initialization.

Main part of #10043
Closes #10164

BREAKING CHANGE:
- Semantics and name of `@AppModule` (now `@NgModule`) changed quite a bit.
  This is actually not breaking as `@AppModules` were not part of rc.4.
  We will have detailed docs on `@NgModule` separately.
- `coreLoadAndBootstrap` and `coreBootstrap` can't be used any more (without migration support).
  Use `bootstrapModule` / `bootstrapModuleFactory` instead.
- All Components listed in routes have to be part of the `declarations` of an NgModule.
  Either directly on the bootstrap module / lazy loaded module, or in an NgModule imported by them.

modules/@angular/router/index.ts

@@ -14,7 +14,7 @@ export {RouterLinkActive} from './src/directives/router_link_active';
 export {RouterOutlet} from './src/directives/router_outlet';
 export {CanActivate, CanActivateChild, CanDeactivate, Resolve} from './src/interfaces';
 export {Event, NavigationCancel, NavigationEnd, NavigationError, NavigationExtras, NavigationStart, Router, RoutesRecognized} from './src/router';
-export {ROUTER_DIRECTIVES, RouterModule} from './src/router_module';
+export {ROUTER_DIRECTIVES, RouterModule, RouterModuleWithoutProviders} from './src/router_module';
 export {RouterOutletMap} from './src/router_outlet_map';
 export {provideRouter} from './src/router_providers';
 export {ActivatedRoute, ActivatedRouteSnapshot, RouterState, RouterStateSnapshot} from './src/router_state';