fix(config): make SHOW_CHROME_EXTENSION_BANNER overridable

react/features/base/config/interfaceConfigWhitelist.js

     'REMOTE_THUMBNAIL_RATIO',
     'SETTINGS_SECTIONS',
     'SHOW_BRAND_WATERMARK',
+    'SHOW_CHROME_EXTENSION_BANNER',
     'SHOW_DEEP_LINKING_IMAGE',
     'SHOW_JITSI_WATERMARK',
     'SHOW_POWERED_BY',