Consolidate getQuota and setQuota methods in User instance

apps/files_trashbin/lib/trashbin.php

apps/files_versions/lib/storage.php

apps/provisioning_api/lib/users.php

apps/user_ldap/lib/user/user.php

lib/private/server.php

lib/private/user/user.php

lib/private/util.php

lib/public/iuser.php

settings/ajax/setquota.php

settings/controller/userscontroller.php