Following up to investigation in T238299, save GW settings as GlobalPreference.
- Modify the script so it GlobalPreference API to store the preferences.
- Make changes to the script so it queries the API to retrieve the preferences.
- Soft-deprecate the current system to save settings (global.js) so it's existing uses don't break. This can be removed completely after all people migrate to the new system.
- Clicking the "Save" button on the Settings page should remove the deprecated config code automatically from global.js and would store the preferences new way (as GlobalPreferences)
- Notify the users of this script about this change via the newsletter.