Remove the mainW, edit widget member variables from the test and use
widgets instantiated on the stack in the tests.
For the data-driven tests, use a static QScopedPointer, which is
reset by a newly introduced TestEnd action.
The book-keeping logic maintaining a list of shortcuts can then be
removed.
The setupShortcut() helpers are simplified and the special case
TestWidget::SendKeyEvent is replaced by a lambda in
keypressConsumption().
Task-number: QTBUG-76493
Change-Id: I15dfa86dfa0666ed8288b7190e37cdb862c261c8
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>