macOS: Fix session restore using wrong monitor's ICC profile

The image load occurred before the window position was restored, so the detected ICC profile was based the window's default position before the desired position was restored.

src/mainwindow.cpp

@@ -222,8 +222,10 @@ void MainWindow::showEvent(QShowEvent *event)
 
     if (!sessionStateToLoad.isEmpty())
     {
-        loadSessionState(sessionStateToLoad, false);
-        sessionStateToLoad = {};
+        QTimer::singleShot(0, this, [this]() {
+            loadSessionState(sessionStateToLoad, false);
+            sessionStateToLoad = {};
+        });
     }
 
     qvApp->addToActiveWindows(this);