add 2fa backup codes app

.gitignore

apps/twofactor_backupcodes/appinfo/app.php

apps/twofactor_backupcodes/appinfo/database.xml

apps/twofactor_backupcodes/appinfo/info.xml

apps/twofactor_backupcodes/appinfo/routes.php

apps/twofactor_backupcodes/css/style.css

apps/twofactor_backupcodes/js/settings.js

apps/twofactor_backupcodes/js/settingsview.js

...ofactor_backupcodes/lib/Controller/SettingsController.php

apps/twofactor_backupcodes/lib/Db/BackupCode.php

apps/twofactor_backupcodes/lib/Db/BackupCodeMapper.php

...wofactor_backupcodes/lib/Provider/BackupCodesProvider.php

apps/twofactor_backupcodes/lib/Service/BackupCodeStorage.php

apps/twofactor_backupcodes/settings/personal.php

apps/twofactor_backupcodes/templates/challenge.php

apps/twofactor_backupcodes/templates/personal.php

...backupcodes/tests/Integration/Db/BackupCodeMapperTest.php

...codes/tests/Integration/Service/BackupCodeStorageTest.php

...kupcodes/tests/Unit/Controller/SettingsControllerTest.php

...ckupcodes/tests/Unit/Provider/BackupCodesProviderTest.php