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/utils.go

@@ -1,33 +0,0 @@
-package hcsshim
-
-import (
-	"io"
-	"syscall"
-
-	"github.com/Microsoft/go-winio"
-)
-
-// makeOpenFiles calls winio.MakeOpenFile for each handle in a slice but closes all the handles
-// if there is an error.
-func makeOpenFiles(hs []syscall.Handle) (_ []io.ReadWriteCloser, err error) {
-	fs := make([]io.ReadWriteCloser, len(hs))
-	for i, h := range hs {
-		if h != syscall.Handle(0) {
-			if err == nil {
-				fs[i], err = winio.MakeOpenFile(h)
-			}
-			if err != nil {
-				syscall.Close(h)
-			}
-		}
-	}
-	if err != nil {
-		for _, f := range fs {
-			if f != nil {
-				f.Close()
-			}
-		}
-		return nil, err
-	}
-	return fs, nil
-}