core: allow extra user private & public fields (#1059)

packages/hydrooj/locales/zh.yaml

@@ -886,7 +886,7 @@ View Contest: 查看比赛
 View contests: 查看比赛
 View Details: 查看详情
 View discussions: 查看讨论
-View domain user displayname: 显示域中用户的显示名
+View domain user private info: 显示域中用户的私有信息
 View hidden contest submission status and scoreboard: 查看隐藏的比赛递交状态和成绩表
 View hidden homework submission status and scoreboard: 查看隐藏的作业递交状态和成绩表
 View hidden problems: 查看隐藏的题目