This commit makes the router directives standalone and refactors some of
the Router injectables to be `providedIn: 'root'` along with factory
functions for initialization.
PR Close#46758
This PR also changes the name of `EmptyOutletComponent` to `ɵEmptyOutletComponent`. This is because `ngcc` requires the node to retain the original name while dts bundler will rename the node is it's only exported using the aliases.
Example typings files:
```ts
declare class EmptyOutletComponent {
}
export {EmptyOutletComponent as ɵEmptyOutletComponent}
```
will be emitted as
```ts
export declare class ɵEmptyOutletComponent {
}
```
PR Close#28833
Andrew Scott