Widget: static widgets which return no data are incorrectly marked as faults and invalidate the layout

[dasgarner]

v4 adds logic which was intended for elements, so that if elements have no data we expire the layout and move on. This is done because elements have no concept of a "No Data Element" to be used when the widget returns no data.

However, static widgets already have a concept of "No data message" which should be used instead of expiring/faulting the widget.

For the avoidance of doubt, when we have a static widget (not elements) we should fault and expire if the requested file is a 404 (i.e. it isn't downloaded at all), but if it is downloaded with data: [] inside, we should continue to render the widget as normal.

[dasgarner]

✅ tested