core&ui: add keep scoreboard hidden option

packages/ui-default/locales/zh.yaml

@@ -419,6 +419,7 @@ Forgot Password and/or Username: 忘记密码和/或用户名
 Forgot password or username?: 忘记密码或者用户名？
 Formula blocks: 公式区块
 Freeze scoreboard with N minutes remaining: 在赛事剩余N分钟时封榜
+Keep scoreboard hidden even after contest ends: 即使比赛结束后也保持成绩表隐藏
 fs_upload: 上传文件
 Gender Visibility: 性别可见性
 Gender: 性别

packages/ui-default/locales/zh_TW.yaml

@@ -418,6 +418,7 @@ Forgot Password and/or Username: 忘記密碼和/或使用者名稱
 Forgot password or username?: 忘記密碼或者使用者名？
 Formula blocks: 公式區塊
 Freeze scoreboard with N minutes remaining: 在賽事剩餘N分鐘時封榜
+Keep scoreboard hidden even after contest ends: 即使比賽結束後也保持成績表隱藏
 fs_upload: 上傳檔案
 Gender Visibility: 性別可見性
 Gender: 性別

packages/ui-default/templates/contest_edit.html

@@ -174,6 +174,17 @@
               value:tdoc.allowPrint|default(false),
               row:false
             }) }}
+            <div style="display: none" class="contest-rule-settings contest-rule--oi contest-rule--strictioi">
+            {{ form.form_checkbox({
+              columns:4,
+              label:'Keep Scoreboard Hidden',
+              name:'keepScoreboardHidden',
+              placeholder:_('Keep scoreboard hidden even after contest ends'),
+              value:tdoc.keepScoreboardHidden|default(false),
+              disabled:true,
+              row:false
+            }) }}
+            </div>
             <div style="display: none" class="contest-rule-settings contest-rule--acm contest-rule--ioi">
             {{ form.form_text({
               columns:4,