feat(route-component): provide matched path in route component

[meeroslav]

Provide the possibility to get the matched path in the RouteComponent, similar to params.
This enables the user to navigate back in the complex nested routes hierarchy with ease.

Example

app.component:

<router>
  <route path="/:username" [exact]="false">
    <app-user *routeComponent></app-user>
  </route>
  <route path="/" redirectTo="/johndoe"></route>
</router>

app.user:

<router>
  <route path="/family" [exact]="false">
    <app-family *routeComponent></app-family>
  </route>
  <route path="/">
    <div *routeComponent>
      ...some info about the user...
    </div>
  </route>
</router>
<a [linkTo]="path$ | async">{{ username$ | async }}</a>

app.user.ts:

export class AppUserComponent implements OnInit {
  username$: Observable<string>;
  path$: Observable<string>;

  constructor(
    private readonly routeParams$: RouteParams<{ username: string }>,
    private readonly routePath$: RoutePath<string>,
  ) { }

  ngOnInit(): void {
    this.path$ = this.routePath$;
    this.username$ = this.routeParams$.pipe(map(params => params.username));
  }
}

If we are at e.g. /janedoe/family/... we can easily go back to /janedoe.