Widgets for tracking KJob instances

 Window class that associates this job with a window given by
 window. This is used by KDialogJobUiDelegate as parent widget
 for error messages, KWidgetJobTracker as parent widget for
 progress dialogs, KIO::AbstractJobInteractionInterface as
 parent widget for rename/skip dialogs and possibly more.
 Overload that takes a QWindow.
 .
 Timestamp handling to update the last user action timestamp
 to the given time. Returns the last user action timestamp.