deprecation notice to plugin compatibility shims
- When qml-common became a thing, we left qs.Widgets shims in place for
plugin compatibility
- It's annoying to need to maintain them when qml-common has any change,
add a warning so we can safely deprecate them in the future
- One shot rename the common stuff to D to make it shorter and nicer to
write
scrollbar: interface style toggle and no scrollbars in the dash
dash: never allow scrollbars
cc: widget sheet cards, header close button and content-sized dialogs
bbedward