…mponent`

Similarly to the symmetry being strengthened between children and loadChildren,
a new loadComponent property will be introduced as the asynchronous version of component.
This will allow for direct single-component lazy loading:

```
{path: 'lazy/a', loadComponent:
  () => import('./lazy/a.component').then(m => m.ACmp)},
{path: 'lazy/b', loadComponent:
  () => import('./lazy/b.component').then(m => m.BCmp)},
```

This option requires that the component being loaded is standalone and
is implemented as a runtime check.

Other notes:
* Components are not loaded until all guards and resolvers complete.
* Loading the component is included in the function passed to the router
  preloading strategy
* `RouteConfigLoadStart` and `RouteConfigLoadEnd` events emit at the
  start and end of the component loading
* `CanLoad` guards _do not_ apply to `loadComponent`. `canActivate`
  should be used instead, just like you would do if it were simply
  `component` instead.