Enhance local backend (#2017)

make local backend able to clone from private

---------
*Sponsored by Kithara Software GmbH*
Co-authored-by: Bruno BELANYI <bruno@belanyi.fr>

pipeline/backend/local/const.go

@@ -0,0 +1,38 @@
+// Copyright 2023 Woodpecker 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 local
+
+import "errors"
+
+// notAllowedEnvVarOverwrites are all env vars that can not be overwritten by step config
+var notAllowedEnvVarOverwrites = []string{
+	"CI_NETRC_MACHINE",
+	"CI_NETRC_USERNAME",
+	"CI_NETRC_PASSWORD",
+	"CI_SCRIPT",
+	"HOME",
+	"SHELL",
+}
+
+var (
+	ErrUnsupportedStepType   = errors.New("unsupported step type")
+	ErrWorkflowStateNotFound = errors.New("workflow state not found")
+)
+
+const netrcFile = `
+machine %s
+login %s
+password %s
+`