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/hns.go

@@ -0,0 +1,23 @@
+package hns
+
+import "fmt"
+
+//go:generate go run ../../mksyscall_windows.go -output zsyscall_windows.go hns.go
+
+//sys _hnsCall(method string, path string, object string, response **uint16) (hr error) = vmcompute.HNSCall?
+
+type EndpointNotFoundError struct {
+	EndpointName string
+}
+
+func (e EndpointNotFoundError) Error() string {
+	return fmt.Sprintf("Endpoint %s not found", e.EndpointName)
+}
+
+type NetworkNotFoundError struct {
+	NetworkName string
+}
+
+func (e NetworkNotFoundError) Error() string {
+	return fmt.Sprintf("Network %s not found", e.NetworkName)
+}