feat(kanban-board): add subtasks localization and enhance task drawer functionality

- Added new localization keys for subtasks in the kanban board JSON file to improve user experience.
- Updated the SubTaskTable component to dispatch enhanced kanban subtask updates upon deletion.
- Enhanced the TaskDrawerHeader to handle deletion of subtasks with appropriate state updates in the kanban context.

worklenz-frontend/public/locales/en/kanban-board.json

@@ -26,5 +26,8 @@
   "noDueDate": "No due date",
   "save": "Save",
   "clear": "Clear",
-  "nextWeek": "Next week"
+  "nextWeek": "Next week",
+  "noSubtasks": "No subtasks",
+  "showSubtasks": "Show subtasks",
+  "hideSubtasks": "Hide subtasks"
 }