Support custom runtime path when launching tasks

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

runtime/v2/binary.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"io"
 	"os"
+	"path/filepath"
 	gruntime "runtime"
 	"strings"
 
@@ -127,6 +128,10 @@ func (b *binary) Start(ctx context.Context, opts *types.Any, onClose func()) (_
 		cancelShimLog()
 		f.Close()
 	}
+	// Save runtime binary path for restore.
+	if err := os.WriteFile(filepath.Join(b.bundle.Path, "runtime"), []byte(b.runtime), 0600); err != nil {
+		return nil, err
+	}
 	client := ttrpc.NewClient(conn, ttrpc.WithOnClose(onCloseWithShimLog))
 	return &shim{
 		bundle: b.bundle,