Replace public operators operator==(), operator!=() of
QItemSelectionRange class to friend methods comparesEqual().
Use QT_CORE_REMOVED_SINCE and removed_api.cpp to get rid of current
comparison methods and replace them with a friend.
Task-number: QTBUG-120304
Change-Id: Ideff990c942d5ee1c89a93ac2081cc5d7067b23f
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
6324075a2d