Move CuraStage into cura.UI module

cura/Stages/__init__.py

@@ -1,2 +0,0 @@
-# Copyright (c) 2017 Ultimaker B.V.
-# Cura is released under the terms of the LGPLv3 or higher.

cura/UI/CuraStage.py

@@ -27,3 +27,6 @@ class CuraStage(Stage):
     @pyqtProperty(QUrl, constant = True)
     def stageMenuComponent(self) -> QUrl:
         return self.getDisplayComponent("menu")
+
+
+__all__ = ["CuraStage"]

plugins/MonitorStage/MonitorStage.py

@@ -2,9 +2,7 @@
 # Cura is released under the terms of the LGPLv3 or higher.
 import os.path
 from UM.Application import Application
-from UM.PluginRegistry import PluginRegistry
-from UM.Resources import Resources
-from cura.Stages.CuraStage import CuraStage
+from cura.UI.CuraStage import CuraStage
 
 
 ##  Stage for monitoring a 3D printing while it's printing.

plugins/PrepareStage/PrepareStage.py

@@ -4,7 +4,7 @@
 import os.path
 from UM.Application import Application
 from UM.PluginRegistry import PluginRegistry
-from cura.Stages.CuraStage import CuraStage
+from cura.UI.CuraStage import CuraStage
 
 ##  Stage for preparing model (slicing).
 class PrepareStage(CuraStage):

plugins/PreviewStage/PreviewStage.py

@@ -4,7 +4,7 @@
 import os.path
 
 from UM.Qt.QtApplication import QtApplication
-from cura.Stages.CuraStage import CuraStage
+from cura.UI.CuraStage import CuraStage
 
 from typing import TYPE_CHECKING, Optional