Create skeleton admin menu for a Roles object

This should have basic resource routes and controllers. Create controller using `php artisan make:controller --resource` to have all the typical controller resource handling generated for you.

- [ ] Controller
- [ ] Route (use named routes)
- [ ] Views (create the most basic views, literally just spit out the required fields or lists and that's it. We'll stylise these in the future)

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*Originals: https://github.com/2bnb/website/projects/1#card-30888822, https://github.com/2bnb/website/projects/1#card-30888764, https://github.com/2bnb/website/projects/1#card-30888750*

Use `php artisan make:controller --resource` to generate a Roles controller. Define a resource route in `routes/web.php` with a named route. Create basic Blade view files (index, create, edit, show) in `resources/views/roles/` that output the required fields. Verify by checking the generated routes with `php artisan route:list`.

索引モデルが issue の本文から書いたものです。