macOS: Apply window file path when creating new NSWindow

Otherwise QWindow::setFilePath() before create() would have no effect.

Change-Id: Ia2171054aa13e21316d525193d330efaf4653dbf
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/cocoa/qcocoawindow.mm

@@ -1292,6 +1292,7 @@ void QCocoaWindow::recreateWindowIfNeeded()
         propagateSizeHints();
         setWindowFlags(window()->flags());
         setWindowTitle(window()->title());
+        setWindowFilePath(window()->filePath());
         setWindowState(window()->windowState());
     } else {
         // Child windows have no NSWindow, link the NSViews instead.