Fix bug when creating pull request (#36166)

Extract from #36105 

Fix #36116
Fix #35912
Fix #20906

models/user/user.go

@@ -1461,3 +1461,15 @@ func GetUserOrOrgIDByName(ctx context.Context, name string) (int64, error) {
 	}
 	return id, nil
 }
+
+// GetUserOrOrgByName returns the user or org by name
+func GetUserOrOrgByName(ctx context.Context, name string) (*User, error) {
+	var u User
+	has, err := db.GetEngine(ctx).Where("lower_name = ?", strings.ToLower(name)).Get(&u)
+	if err != nil {
+		return nil, err
+	} else if !has {
+		return nil, ErrUserNotExist{Name: name}
+	}
+	return &u, nil
+}