Service provider and other cleanup

- Removed old 'exposeTranslations' system to instead use new component
 option system.
- Extracted validation rules into their own service provider.
- Cleaned up some formatting/comments in the repos.

app/Entities/Repos/PageRepo.php

@@ -11,7 +11,6 @@ use BookStack\Entities\Page;
 use BookStack\Entities\PageRevision;
 use BookStack\Exceptions\MoveOperationException;
 use BookStack\Exceptions\NotFoundException;
-use BookStack\Exceptions\NotifyException;
 use BookStack\Exceptions\PermissionsException;
 use BookStack\Facades\Activity;
 use Exception;