support yaml/json/toml configuration format, make ini deprecated (#3599)

pkg/config/v1/validation/validation.go

@@ -0,0 +1,28 @@
+// Copyright 2023 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package validation
+
+import (
+	"errors"
+)
+
+type Warning error
+
+func AppendError(err error, errs ...error) error {
+	if len(errs) == 0 {
+		return err
+	}
+	return errors.Join(append([]error{err}, errs...)...)
+}