Exclude cached routes with randomly generated names

[bakerkretzmar]

When you run php artisan route:cache, Laravel assigns unnamed routes a unique, randomly generated name that looks something like generated::ZRopaJJwzA27wRLa.

Ziggy should ignore these routes because they don't actually have explicit names assigned by the developer, so including them in the output will increase its size considerably and could expose information that should not be visible client-side.

To that end, this PR just filters out any route whose name starts with generated::.

---

I tried to actually cache the routes in a test, but Testbench doesn't support this out of the box and I kept getting very weird Opis/Closure errors. Here's what I was trying, more or less:

    // tests/TestCase.php

    protected function cacheRoutes()
    {
        $routes = app('router')->getRoutes();
        $routes->refreshNameLookups();
        $routes->refreshActionLookups();

        foreach ($routes as $route) {
            $route->prepareForSerialization();
        }

        $this->laravelVersion(7)
            ? app('router')->setCompiledRoutes($routes->compile())
            : app('router')->setRoutes($routes);
    }