Add ability to get a stack of GoRoutes that match a given name

[esDotDev]

There are times when we want to retrieve the .path value for a given route, using the name.

For example, I might have a view that need to check whether it is currently on the search page, but it only has the route name available to use.

So, given this route:

GoRoute(
  path: '/search/:keywords',
  name: SearchPage.routeName,
)

I want to check whether this is my current route somewhere down the tree, using SearchPage.routeName to do it:

string searchPath = router.routesForName(SearchPage.routeName).last.path;
searchPath = searchPath.split['/'].first(); // gets 'search'
if(goRouter.location.contains('/$searchPath/')){
  // we're on the search page
}

[csells]

I believe this can be built with GoRouter.of(context).routerDelegate.matches today.