Allow user to specify an ad hoc name when submitting ad hoc attendance

Currently, all ad-hocs have their attendance listed under the general "Ad-Hoc" category. This makes sense as is, because we dont want to have to update the database every time there is a new adhoc or if an adhoc is not recreated.

However, it would be cool if, when a user selects the "ad-hoc" option in the attendance dropdown, a textbox appears that lets them type in a label for their attendance.

This would also make it easier for eboard members to figure out what an attendance is on the attendance history page when they are trying to approve it.

先找到出席下拉選單和處理臨時提交的程式碼，接著追蹤出席記錄如何顯示在歷史頁面上。在決定使用者提供的標籤應放在哪裡之前，確認現有臨時記錄的儲存方式。完成的標準是：臨時提交可以包含標籤，且 eboard 成員能在出席歷史中看到該標籤。

由索引模型根據 Issue 內容生成。