Introduce containerd-shim-runhcs-v1 on Windows

Implements the containerd-shim-runhcs-v1 shim on Windows for the runtime
v2 shim API.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>

vendor/github.com/Microsoft/hcsshim/internal/guid/guid.go

@@ -0,0 +1,22 @@
+package guid
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+)
+
+type GUID [16]byte
+
+func New() GUID {
+	g := GUID{}
+	_, err := io.ReadFull(rand.Reader, g[:])
+	if err != nil {
+		panic(err)
+	}
+	return g
+}
+
+func (g GUID) String() string {
+	return fmt.Sprintf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x-%02x", g[3], g[2], g[1], g[0], g[5], g[4], g[7], g[6], g[8:10], g[10:])
+}