fix(router): make locationSyncBootstrapListener public due to change in output after TS 2.7 update in #22669 (#22896)

PR Close #22896

packages/router/upgrade/src/upgrade.ts

@@ -38,7 +38,7 @@ import {UpgradeModule} from '@angular/upgrade/static';
 export const RouterUpgradeInitializer = {
   provide: APP_BOOTSTRAP_LISTENER,
   multi: true,
-  useFactory: locationSyncBootstrapListener,
+  useFactory: locationSyncBootstrapListener as(ngUpgrade: UpgradeModule) => () => void,
   deps: [UpgradeModule]
 };