fixup! Cleanup widgetsModel and add tests

The change removed `getAllWidgetComponentsWithoutShortcuts` as it
seemed unused/duplicated and replaced it with `getWidgetsByComponentKey`

Sadly the method isn't exactly the same and doesn't filter widgets
with null widgetInfo at the origin, let's add back the checks where
`getAllWidgetComponentsWithoutShortcuts` was used previously.

Change-Id: I4333a0f8cbbaecb9b5fa5f2543b982a121c79e27