QtIFW

Fix extracted files list formation in ExtractArchive operation

In ExtractArchive, the ConnectionType used to connect signal
'currentFileChanged' to slot 'fileFinished' was changed to
Qt::AutoConnection in c8de51cadbc5855ca1e77d038d7f09bf60d059ee,
rather than using Qt::DirectConnection explicitly.

Now the connection type defaults to queued as the sender and
receiver live on a different thread. This seems to cause an issue
where the slot function is not invoked for every emitted
'currentFileChanged' signal before returning from
ExtractArchiveOperation::performOperation(). This can happen
randomly on some installer runs, leaving entries out from
ExtractArchive's "files" list for some components.

The list formation works fine with Qt::DirectConnection, however
reverting to this behavior might be a bad practice as it leaves
'fileFinished' vulnerable to accidental calls from another thread
if we change the behavior in the future. Rather move the extracted
files list formation to ExtractArchiveOperation::Callback like we
already do for backup files.

Task-number: QTIFW-1239
Change-Id: I7dbe73abefe00814e8652432d8abdbcaa83e0bac
Reviewed-by: Iikka Eklund <iikka.eklund@qt.io>
Reviewed-by: Katja Marttila <katja.marttila@qt.io>