Support priv/unpriv image extraction

Optionally add back privileged extraction which can be enabled with
LUET_PRIVILEGED_EXTRACT=true

Signed-off-by: Ettore Di Giacinto <mudler@sabayon.org>

vendor/github.com/moby/buildkit/executor/executor.go

@@ -0,0 +1,39 @@
+package executor
+
+import (
+	"context"
+	"io"
+	"net"
+
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/solver/pb"
+)
+
+type Meta struct {
+	Args           []string
+	Env            []string
+	User           string
+	Cwd            string
+	Tty            bool
+	ReadonlyRootFS bool
+	ExtraHosts     []HostIP
+	NetMode        pb.NetMode
+	SecurityMode   pb.SecurityMode
+}
+
+type Mount struct {
+	Src      cache.Mountable
+	Selector string
+	Dest     string
+	Readonly bool
+}
+
+type Executor interface {
+	// TODO: add stdout/err
+	Exec(ctx context.Context, meta Meta, rootfs cache.Mountable, mounts []Mount, stdin io.ReadCloser, stdout, stderr io.WriteCloser) error
+}
+
+type HostIP struct {
+	Host string
+	IP   net.IP
+}