added sftp client implementation

pkg/provider/sftp/error.go

@@ -0,0 +1,45 @@
+// Copyright (C) 2022 Marius Schellenberger
+package sftp
+
+import (
+	"errors"
+	"io/fs"
+
+	"github.com/pkg/sftp"
+)
+
+var ErrNotConnected = errors.New("sftp not connected")
+
+type connError struct{}
+
+func (connError) Remove(_ string) error {
+	return ErrNotConnected
+}
+
+func (connError) Open(_ string) (*sftp.File, error) {
+	return nil, ErrNotConnected
+}
+
+func (connError) OpenFile(_ string, _ int) (*sftp.File, error) {
+	return nil, ErrNotConnected
+}
+
+func (connError) Stat(_ string) (fs.FileInfo, error) {
+	return nil, ErrNotConnected
+}
+
+func (connError) ReadDir(_ string) ([]fs.FileInfo, error) {
+	return nil, ErrNotConnected
+}
+
+func (connError) MkdirAll(_ string) error {
+	return ErrNotConnected
+}
+
+func (connError) Wait() error {
+	return ErrNotConnected
+}
+
+func (connError) Close() error {
+	return nil
+}