Possible imports are now also parsed for items in item library.
They are only shown in case the search string is not empty.
Starting a drag of unimported item will automatically add the import.
Added a small manhattanlength check to the start of the drag to
avoid unwanted import additions on clicks.
Also fixed the item sorting to alphabetical order within categories.
Task-number: QDS-3825
Change-Id: I93366182af3fd7eda38bf94d53807393ecf92a08
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>