update github.com/rootless-containers/rootlesskit to v2

Contains a breaking change but also besides this renovate is not able to
update the import paths so this needs to be done by hand.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

vendor/github.com/rootless-containers/rootlesskit/v2/pkg/lowlevelmsgutil/lowlevelmsgutil.go

@@ -0,0 +1,65 @@
+// Package lowlevelmsgutil provides utility for JSON message with uint32le header
+package lowlevelmsgutil
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+const (
+	maxLength = 1 << 16
+)
+
+func MarshalToWriter(w io.Writer, x interface{}) (int, error) {
+	b, err := json.Marshal(x)
+	if err != nil {
+		return 0, err
+	}
+	if len(b) > maxLength {
+		return 0, fmt.Errorf("bad message length: %d (max: %d)", len(b), maxLength)
+	}
+	h := make([]byte, 4)
+	binary.LittleEndian.PutUint32(h, uint32(len(b)))
+	return w.Write(append(h, b...))
+}
+
+func UnmarshalFromReader(r io.Reader, x interface{}) (int, error) {
+	hdr := make([]byte, 4)
+	n, err := r.Read(hdr)
+	if err != nil {
+		return n, err
+	}
+	if n != 4 {
+		return n, fmt.Errorf("read %d bytes, expected 4 bytes", n)
+	}
+	bLen := binary.LittleEndian.Uint32(hdr)
+	if bLen > maxLength || bLen < 1 {
+		return n, fmt.Errorf("bad message length: %d (max: %d)", bLen, maxLength)
+	}
+	b := make([]byte, bLen)
+	n, err = r.Read(b)
+	if err != nil {
+		return 4 + n, err
+	}
+	if n != int(bLen) {
+		return 4 + n, fmt.Errorf("read %d bytes, expected %d bytes", n, bLen)
+	}
+	return 4 + n, json.Unmarshal(b, x)
+}
+
+func Marshal(x interface{}) ([]byte, error) {
+	var b bytes.Buffer
+	_, err := MarshalToWriter(&b, x)
+	return b.Bytes(), err
+}
+
+func Unmarshal(b []byte, x interface{}) error {
+	n, err := UnmarshalFromReader(bytes.NewReader(b), x)
+	if n != len(b) {
+		return fmt.Errorf("read %d bytes, expected %d bytes", n, len(b))
+	}
+	return err
+}