Support Google's CCPA framework

[benlk]

General note: https://privacy.google.com/businesses/rdp/

Specific implementation details: https://support.google.com/admanager/answer/9598414

This passes a configuration item to the GPT tag, which is mostly created and handled by jquery.dfp.js, which is drawn from the dfoPoptions object in https://github.com/INN/doubleclick-for-wp/blob/f106d4733b237f4b359fd011758d56fe46e04f4e/js/vendor/jquery.dfp.js/jquery.dfp.js#L243-L246

We may need to patch jQuery.dfp.js to support this, though, since jQuery.dfp.js hasn't received a tagged release since 2016: https://github.com/coop182/jquery.dfp.js/releases

There's a slightly-updated downstream version at https://github.com/maxx0r/jquery.dfp.js/commit/1fbab9364e810ff8bc2ff6446957d399106eb728

• [ ] figure out how to add the config item to dfp
• [ ] add the configuration item to dfp
• [ ] add a checkbox in the plugin settings
• [ ] admonish site admins to mention ads in their https://wordpress.org/support/article/settings-privacy-screen/