[8.x] Improves Support\Reflector to support checking interfaces

[hassanhe]

Since ReflectionClass already may represent an interface, we may check for interface existence as part of checking parameter subclass.

isParameterSubclassOf is used in two places for model route binding:

• Routing\RouteSignatureParameters
• Broadcasting\Broadcasters\Broadcaster

This improvement helps with implicit binding when the parameter is an interface served from the container

use Illuminate\Contracts\Routing\UrlRoutable;

interface MyUrlRoutableModel extends UrlRoutable {
 //
}

Route::get('/{model}', function (MyUrlRoutableModel $model) {
   // $model binds correctly
});

Fixes #11791