Ensure support for Dirty AMP

[westonruter]

AMP can be used as a component library even on non-AMP pages. This is called “Dirty AMP”. When a theme is doing this they will have to enqueue the AMP component scripts on their own whereas when AMP is active it will automatically add the component scripts to the head based on which components are actually used in the page. So if AMP components are being used like this on non-AMP pages then we need to make sure that the AMP component scripts are not duplicated.