Disable updates checkboxes when performing updates

There's no point in interacting with it while the process is ongoing.

discover/qml/UpdatesPage.qml

@@ -174,6 +174,7 @@ DiscoverPage
                         Layout.alignment: Qt.AlignVCenter
                         checked: model.checked == Qt.Checked
                         onClicked: model.checked = (model.checked==Qt.Checked ? Qt.Unchecked : Qt.Checked)
+                        enabled: !resourcesUpdatesModel.isProgressing
                     }
 
                     Kirigami.Icon {