Move some issue methods as functions (#19255)

* Move some issue methods as functions

* Fix bug

routers/api/v1/repo/pull.go

@@ -560,7 +560,7 @@ func EditPullRequest(ctx *context.APIContext) {
 			labels = append(labels, orgLabels...)
 		}
 
-		if err = issue.ReplaceLabels(labels, ctx.Doer); err != nil {
+		if err = models.ReplaceIssueLabels(issue, labels, ctx.Doer); err != nil {
 			ctx.Error(http.StatusInternalServerError, "ReplaceLabelsError", err)
 			return
 		}

routers/web/repo/issue.go

@@ -2595,7 +2595,7 @@ func updateAttachments(item interface{}, files []string) error {
 	if len(files) > 0 {
 		switch content := item.(type) {
 		case *models.Issue:
-			err = content.UpdateAttachments(files)
+			err = models.UpdateIssueAttachments(content.ID, files)
 		case *models.Comment:
 			err = content.UpdateAttachments(files)
 		default:

routers/web/repo/issue_label.go

@@ -191,7 +191,7 @@ func UpdateIssueLabel(ctx *context.Context) {
 			// detach if any issues already have label, otherwise attach
 			action = "attach"
 			for _, issue := range issues {
-				if issue.HasLabel(label.ID) {
+				if models.HasIssueLabel(issue.ID, label.ID) {
 					action = "detach"
 					break
 				}