Refactor Route Resolving and Dispatch (#2425)

- Split DispatchRoute. This allows us to run middleware after we figure out which route we're on, but before we actually execute the controller for that route.
- By making the route name explicitly available to middlewares, applications like CSRF and floodgate can set patterns based on route names instead of the path, which is an implementation detail.
- Support using route name match for CSRF extender, deprecate path match

src/Http/HttpServiceProvider.php

@@ -19,7 +19,7 @@ class HttpServiceProvider extends AbstractServiceProvider
     public function register()
     {
         $this->app->singleton('flarum.http.csrfExemptPaths', function () {
-            return ['/api/token'];
+            return ['token'];
         });
 
         $this->app->bind(Middleware\CheckCsrfToken::class, function ($app) {