Switch from containers/image to go-containerregistry (#140)

* Vendor changes for go-containerregistry switch.

* Manual changes for go-containerregistry switch.

The biggest change is refactoring the tarball unpacking.

* Pull more of container-diff out.

* More vendor removals.

* More unit tests.

vendor/github.com/Microsoft/hcsshim/preparelayer.go

@@ -1,46 +0,0 @@
-package hcsshim
-
-import (
-	"sync"
-
-	"github.com/sirupsen/logrus"
-)
-
-var prepareLayerLock sync.Mutex
-
-// PrepareLayer finds a mounted read-write layer matching layerId and enables the
-// the filesystem filter for use on that layer.  This requires the paths to all
-// parent layers, and is necessary in order to view or interact with the layer
-// as an actual filesystem (reading and writing files, creating directories, etc).
-// Disabling the filter must be done via UnprepareLayer.
-func PrepareLayer(info DriverInfo, layerId string, parentLayerPaths []string) error {
-	title := "hcsshim::PrepareLayer "
-	logrus.Debugf(title+"flavour %d layerId %s", info.Flavour, layerId)
-
-	// Generate layer descriptors
-	layers, err := layerPathsToDescriptors(parentLayerPaths)
-	if err != nil {
-		return err
-	}
-
-	// Convert info to API calling convention
-	infop, err := convertDriverInfo(info)
-	if err != nil {
-		logrus.Error(err)
-		return err
-	}
-
-	// This lock is a temporary workaround for a Windows bug. Only allowing one
-	// call to prepareLayer at a time vastly reduces the chance of a timeout.
-	prepareLayerLock.Lock()
-	defer prepareLayerLock.Unlock()
-	err = prepareLayer(&infop, layerId, layers)
-	if err != nil {
-		err = makeErrorf(err, title, "layerId=%s flavour=%d", layerId, info.Flavour)
-		logrus.Error(err)
-		return err
-	}
-
-	logrus.Debugf(title+"succeeded flavour=%d layerId=%s", info.Flavour, layerId)
-	return nil
-}