Add migrations to package

Ideally we'd ship with a migration to add the github and github_token columns to the users table for Laravel.

Make use of the same way of ignoring migrations in Laravel first party packages if people don't want these to run automatically with the packge: https://laravel.com/docs/8.x/billing#database-migrations