Add new context menu item: Copy Custom Field Name (#2045)

* Add "Copy custom field name" context menu item

* Title case context menu string

* Improve Copy Custom Field Name logic

* Move CopyClickedElement to runtime.background

* Update dependencies

* Add comments, refactor logic, add failure messages

* Fix typo and linting

* Fix typos

* Move null check inside function

src/background/runtime.background.ts

@@ -195,6 +195,8 @@ export default class RuntimeBackground {
                     type: 'info',
                 });
                 break;
+            case 'getClickedElementResponse':
+                this.platformUtilsService.copyToClipboard(msg.identifier, { window: window });
             default:
                 break;
         }