fix(dialout) whitelist dialout flag

react/features/base/config/interfaceConfigWhitelist.js

     'DISABLE_TRANSCRIPTION_SUBTITLES',
     'DISABLE_VIDEO_BACKGROUND',
     'DISPLAY_WELCOME_PAGE_CONTENT',
+    'ENABLE_DIAL_OUT',
     'ENABLE_FEEDBACK_ANIMATION',
     'ENFORCE_NOTIFICATION_AUTO_DISMISS_TIMEOUT',
     'FILM_STRIP_MAX_HEIGHT',