Create MaterialsSyncDialog from a Python function

Rather than from the QML.
This allows creating this dialogue from a message button without needing to put it in the base application.

Contributes to issue CURA-8609.

cura/Machines/Models/MaterialManagementModel.py

@@ -10,6 +10,7 @@ import zipfile  # To export all materials in a .zip archive.
 from UM.i18n import i18nCatalog
 from UM.Logger import Logger
 from UM.Message import Message
+from UM.Resources import Resources  # To find QML files.
 from UM.Signal import postponeSignals, CompressTechnique
 
 import cura.CuraApplication  # Imported like this to prevent circular imports.
@@ -28,6 +29,10 @@ class MaterialManagementModel(QObject):
     :param The base file of the material is provided as parameter when this emits
     """
 
+    def __init__(self, parent: QObject = None):
+        super().__init__(parent)
+        self._sync_all_dialog = None  # type: Optional[QObject]
+
     @pyqtSlot("QVariant", result = bool)
     def canMaterialBeRemoved(self, material_node: "MaterialNode") -> bool:
         """Can a certain material be deleted, or is it still in use in one of the container stacks anywhere?
@@ -262,6 +267,18 @@ class MaterialManagementModel(QObject):
         except ValueError:  # Material was not in the favorites list.
             Logger.log("w", "Material {material_base_file} was already not a favorite material.".format(material_base_file = material_base_file))
 
+    @pyqtSlot()
+    def openSyncAllWindow(self) -> None:
+        """
+        Opens the window to sync all materials.
+        """
+        if self._sync_all_dialog is None:
+            qml_path = Resources.getPath(cura.CuraApplication.CuraApplication.ResourceTypes.QmlFiles, "Preferences", "Materials", "MaterialsSyncDialog.qml")
+            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.show()
+
     @pyqtSlot(result = QUrl)
     def getPreferredExportAllPath(self) -> QUrl:
         """

resources/qml/Preferences/Materials/MaterialsPage.qml

@@ -201,7 +201,7 @@ Item
             onClicked:
             {
                 forceActiveFocus();
-                materialsSyncDialog.show();
+                base.materialManagementModel.openSyncAllWindow();
             }
             visible: Cura.MachineManager.activeMachine.supportsMaterialExport
         }
@@ -399,9 +399,4 @@ Item
     {
         id: messageDialog
     }
-
-    MaterialsSyncDialog
-    {
-        id: materialsSyncDialog
-    }
 }

resources/qml/Preferences/Materials/MaterialsSyncDialog.qml

@@ -9,6 +9,8 @@ import UM 1.2 as UM
 Window
 {
     id: materialsSyncDialog
+    property variant catalog: UM.I18nCatalog { name: "cura" }
+
     title: catalog.i18nc("@title:window", "Sync materials with printers")
     minimumWidth: UM.Theme.getSize("modal_window_minimum").width
     minimumHeight: UM.Theme.getSize("modal_window_minimum").height