[Feat] Sort routes by `path` and `exact` on registering

[meeroslav]

This is precondition to guards on RouteComponent using structural directive.

At the moment, each route with structural directive will be registered asynchronously, landing in the routes array most likely after wildcard/catch-all route. Additionally, this allows user to define routes without worrying about the correct order.

Rough logic:

this.routes$ = this._routes$.pipe(scan((routes, route) => {
  routes = routes.concat(route).sort((a, b) => {
    if (b.path < a.path) { return -1; }
    if (a.path < b.path) { return 1; }
    if (a.options.exact < b.options.exact) { return -1; } // additional checks for missing `exact` param needed
    if (a.options.exact > b.options.exact) { return 1; }
    return 0;
  });
  return routes;
}));