Ensure that edit & help menu have the right styling

They were still using the default Qt Menu instead of Cura.Menu

CURA-8928

resources/qml/Menus/EditMenu.qml

@@ -7,13 +7,13 @@ import QtQuick.Controls 2.1
 import UM 1.6 as UM
 import Cura 1.0 as Cura
 
-Menu
+Cura.Menu
 {
     title: catalog.i18nc("@title:menu menubar:toplevel", "&Edit")
 
     Cura.MenuItem { action: Cura.Actions.undo }
     Cura.MenuItem { action: Cura.Actions.redo }
-    MenuSeparator { }
+    Cura.MenuSeparator { }
     Cura.MenuItem { action: Cura.Actions.selectAll }
     Cura.MenuItem { action: Cura.Actions.arrangeAll }
     Cura.MenuItem { action: Cura.Actions.multiplySelection }
@@ -21,7 +21,7 @@ Menu
     Cura.MenuItem { action: Cura.Actions.deleteAll }
     Cura.MenuItem { action: Cura.Actions.resetAllTranslation }
     Cura.MenuItem { action: Cura.Actions.resetAll }
-    MenuSeparator { }
+    Cura.MenuSeparator { }
     Cura.MenuItem { action: Cura.Actions.groupObjects }
     Cura.MenuItem { action: Cura.Actions.mergeObjects }
     Cura.MenuItem { action: Cura.Actions.unGroupObjects }

resources/qml/Menus/HelpMenu.qml

@@ -8,7 +8,7 @@ import UM 1.5 as UM
 import Cura 1.0 as Cura
 
 
-Menu
+Cura.Menu
 {
     id: helpMenu
     title: catalog.i18nc("@title:menu menubar:toplevel", "&Help")