Allow adding multiple per object settings at once

This reuses the "GUI pattern" of the main setting visibility page.
CURA-1799

plugins/PerObjectSettingsTool/PerObjectItem.qml

@@ -16,17 +16,17 @@ UM.TooltipArea
     width: childrenRect.width;
     height: childrenRect.height;
 
-    Button
+    CheckBox
     {
         id: check
 
         text: definition.label
+        checked: addedSettingsModel.getVisible(model.key)
 
         onClicked:
         {
-            addedSettingsModel.setVisible(model.key, true);
-            settingPickDialog.visible = false
-            UM.ActiveTool.forceUpdate()
+            addedSettingsModel.setVisible(model.key, checked);
+            UM.ActiveTool.forceUpdate();
         }
     }
 }

plugins/PerObjectSettingsTool/PerObjectSettingsPanel.qml

@@ -377,7 +377,7 @@ Item {
 
         rightButtons: [
             Button {
-                text: catalog.i18nc("@action:button", "Cancel");
+                text: catalog.i18nc("@action:button", "Close");
                 onClicked: {
                     settingPickDialog.visible = false;
                 }