Reset page index to 0 when re-opening sync dialogue

When the user previously opened the dialog and advanced through the pages, but closes the window, then they'll probably have to restart when they want to try it again.

Contributes to issue CURA-8609.

cura/Machines/Models/MaterialManagementModel.py

@@ -277,6 +277,7 @@ class MaterialManagementModel(QObject):
             self._sync_all_dialog = cura.CuraApplication.CuraApplication.getInstance().createQmlComponent(qml_path, {})
         if self._sync_all_dialog is None:  # Failed to load QML file.
             return
+        self._sync_all_dialog.setProperty("pageIndex", 0)
         self._sync_all_dialog.show()
 
     @pyqtSlot(result = QUrl)

resources/qml/Preferences/Materials/MaterialsSyncDialog.qml

@@ -20,6 +20,8 @@ Window
     height: minimumHeight
     modality: Qt.ApplicationModal
 
+    property alias pageIndex: swipeView.currentIndex
+
     SwipeView
     {
         id: swipeView