[10.x] Can set custom Response for denial within Gate@inspect()

[cosmastech]

Allow setting the Response returned when a Gate's inspect() method fails. This is particularly helpful when using the can middleware.

class AppServiceProvider extends ServiceProvider
{
    public function boot()
    {
        Gate::setDenialResponse(Response::denyAsNotFound());
    }
}

While it's possible to return a response from a Policy's method (or throw an Exception), this can lead to a lot of duplicated code. I personally think it makes more sense to return a bool in most cases.

Being able to deny as not found is beneficial for security, as it doesn't expose whether a resource is matched or if the user is just unauthorized.