(bug 44745) Detaching toolbar from listview and claimlistview widget

The change set adds a new addtoolbar widget which basically acts as a wrapper for a
widget offering add functionality (similar to the edittoolbar widget). All direct
toolbar references are removed from the listview and claimlistview widget with the
interaction between the listview widget and the toolbar widget being managed via
events.
Any toolbar initialization will be moved into a separate controller in an upcoming
change set.

Change-Id: I77272d012dc2b240178f42e01844008f1e09a329
Merge "(bug 44745) Detaching toolbar from listview and claimlistview widget"