Fix daemon key provider service

Handles missing keys if user is an admin or the server owner. Step in the right direction for #733 where all users have their own keys now. Still need to address admin status revocation in order to fully address that issue.

app/Contracts/Repository/SubuserRepositoryInterface.php

@@ -33,7 +33,7 @@ interface SubuserRepositoryInterface extends RepositoryInterface
      *
      * @throws \Pterodactyl\Exceptions\Repository\RecordNotFoundException
      */
-    public function getWithPermissionsUsingUserAndServer($user, $server);
+    public function getWithPermissionsUsingUserAndServer(int $user, int $server): Subuser;
 
     /**
      * Find a subuser and return with server and permissions relationships.