QMessageBox has text values that an accessible client should be able to
read directly without having to navigate through the text labels.
Add test coverage.
Windows Narrator is inconsistent in reading the contents of a message
box. It might skip them completely, even though the text property is
read through the interface.
Task-number: QTBUG-101585
Change-Id: I639c2210a627733c093743790c6a6b83f4bb80d0
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
56d6a36020