feat: Add sorting by exclusive labels (issue priority) (#33206)

Fix #2616

This PR adds a new sort option for exclusive labels.

For exclusive labels, a new property is exposed called "order", while in
the UI options are populated automatically in the `Sort` column (see
screenshot below) for each exclusive label scope.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/user/setting/applications.go

@@ -43,8 +43,9 @@ func ApplicationsPost(ctx *context.Context) {
 
 	_ = ctx.Req.ParseForm()
 	var scopeNames []string
+	const accessTokenScopePrefix = "scope-"
 	for k, v := range ctx.Req.Form {
-		if strings.HasPrefix(k, "scope-") {
+		if strings.HasPrefix(k, accessTokenScopePrefix) {
 			scopeNames = append(scopeNames, v...)
 		}
 	}