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/hns/hnsfuncs.go

@@ -0,0 +1,42 @@
+package hns
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/Microsoft/hcsshim/internal/hcserror"
+	"github.com/Microsoft/hcsshim/internal/interop"
+	"github.com/sirupsen/logrus"
+)
+
+func hnsCall(method, path, request string, returnResponse interface{}) error {
+	var responseBuffer *uint16
+	logrus.Debugf("[%s]=>[%s] Request : %s", method, path, request)
+
+	err := _hnsCall(method, path, request, &responseBuffer)
+	if err != nil {
+		return hcserror.New(err, "hnsCall ", "")
+	}
+	response := interop.ConvertAndFreeCoTaskMemString(responseBuffer)
+
+	hnsresponse := &hnsResponse{}
+	if err = json.Unmarshal([]byte(response), &hnsresponse); err != nil {
+		return err
+	}
+
+	if !hnsresponse.Success {
+		return fmt.Errorf("HNS failed with error : %s", hnsresponse.Error)
+	}
+
+	if len(hnsresponse.Output) == 0 {
+		return nil
+	}
+
+	logrus.Debugf("Network Response : %s", hnsresponse.Output)
+	err = json.Unmarshal(hnsresponse.Output, returnResponse)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}