move new inject button to existing edit form

- revert refactoring of building editableList (not needed now)
- remove node button modifier click & tray.show feature
- add inject button to editableList [buttons] array
- add `id` option to editableList to permit DOM access after creation
- get the new inject button via its `id` and float it to the right
- removed the popup tray buttons i18n entries

packages/node_modules/@node-red/editor-client/src/js/ui/common/editableList.js

@@ -18,7 +18,7 @@
 /**
  * options:
  *   - addButton : boolean|string - text for add label, default 'add'
- *   - buttons : array - list of custom buttons (objects with fields 'label', 'icon', 'title', 'click')
+ *   - buttons : array - list of custom buttons (objects with fields 'id', 'label', 'icon', 'title', 'click')
  *   - height : number|'auto'
  *   - resize : function - called when list as a whole is resized
  *   - resizeItem : function(item) - called to resize individual item
@@ -103,6 +103,9 @@
                         }
                     });
 
+                if (button.id) {
+                    element.attr("id", button.id);
+                }
                 if (button.title) {
                     element.attr("title", button.title);
                 }