GTK4 port

Merged Paolo Bacchilega requested to merge wip/gtk4 into master

This is File-Roller ported to GTK4. There is some space for improvement as we still use some deprecated API such as GSimpleAsyncResult and GtkTreeView, also we link to libadwaita just to get the new GNOME look but no Adwaita widget is used at the moment. About Drag-and-Drop the only supported action is dropping a single file in a File-Roller window to add it to an archive or to open it if it's an archive itself, but there is still no way to extract files from the archive dropping them in a Nautilus window. Overall I'm happy with the porting, therefore the merge request.

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