add route named `login` if not exists

[jpuck]

By convention, laravel assumes a route named login exists to redirect unauthenticated requests.

This package names its route shibboleth-login because it's designed to work alongside other authentication providers, such as the default scaffolding provided by artisan. But if this is the only authentication provider, then that name will need to be manually declared. e.g.

Route::name('login')->get('/login', '\\'.Route::getRoutes()->getByName('shibboleth-login')->getActionName());

or more readable, but with a redirect:

Route::redirect('/login', '/shibboleth-login')->name('login');

One solution to this problem could be to declare the route named login if it doesn't already exist. However, this might get tricky with route loading and precedence order.

Another possible solution would be to allow a configuration to rename the routes.