Update hcsshim and go-winio vendoring

* Update hcsshim to v0.8.14
* Update go-winio to v0.4.16

This brings in some vhd package changes from winio, and the compute storage api bindings for
the shim. This is to facilitate some coming functionality for the windows snapshotter
as well as possibly for future work down the line for the windows differ.

Signed-off-by: Daniel Canter <dcanter@microsoft.com>

vendor/github.com/Microsoft/hcsshim/computestorage/import.go

@@ -0,0 +1,41 @@
+package computestorage
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/Microsoft/hcsshim/internal/oc"
+	"go.opencensus.io/trace"
+)
+
+// ImportLayer imports a container layer.
+//
+// `layerPath` is a path to a directory to import the layer to. If the directory
+// does not exist it will be automatically created.
+//
+// `sourceFolderpath` is a pre-existing folder that contains the layer to
+// import.
+//
+// `layerData` is the parent layer data.
+func ImportLayer(ctx context.Context, layerPath, sourceFolderPath string, layerData LayerData) (err error) {
+	title := "hcsshim.ImportLayer"
+	ctx, span := trace.StartSpan(ctx, title)
+	defer span.End()
+	defer func() { oc.SetSpanStatus(span, err) }()
+	span.AddAttributes(
+		trace.StringAttribute("layerPath", layerPath),
+		trace.StringAttribute("sourceFolderPath", sourceFolderPath),
+	)
+
+	bytes, err := json.Marshal(layerData)
+	if err != nil {
+		return err
+	}
+
+	err = hcsImportLayer(layerPath, sourceFolderPath, string(bytes))
+	if err != nil {
+		return fmt.Errorf("failed to import layer: %s", err)
+	}
+	return nil
+}