[ChangeLog][QtCore][QSettings] The INI file reader now supports
keys encoded with UTF-8, as well as the %-encoded format. Writing
the keys back to the INI file is still done using %-encoded format.
This change does not touch the way the *values* are handled - they
are both read and written in UTF-8.
Drive-by: remove misleading comments from the reading algorithm.
Task-number: QTBUG-99401
Change-Id: I6a83cbf24d919a499540403688615f93cb195e93
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
6e9a3d4209