Organize Toolbox (marketplace) qml files according to type

CURA-6569

plugins/Toolbox/resources/qml/pages/ToolboxLoadingPage.qml

@@ -0,0 +1,23 @@
+// Copyright (c) 2018 Ultimaker B.V.
+// Toolbox is released under the terms of the LGPLv3 or higher.
+
+import QtQuick 2.10
+import QtQuick.Controls 1.4
+import QtQuick.Controls.Styles 1.4
+
+Rectangle
+{
+    id: page
+    width: parent.width
+    height: parent.height
+    color: "transparent"
+    Label
+    {
+        text: catalog.i18nc("@info", "Fetching packages...")
+        anchors
+        {
+            centerIn: parent
+        }
+        renderType: Text.NativeRendering
+    }
+}