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/interop/interop.go

@@ -0,0 +1,27 @@
+package interop
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go interop.go
+
+//sys coTaskMemFree(buffer unsafe.Pointer) = ole32.CoTaskMemFree
+
+func ConvertAndFreeCoTaskMemString(buffer *uint16) string {
+	str := syscall.UTF16ToString((*[1 << 29]uint16)(unsafe.Pointer(buffer))[:])
+	coTaskMemFree(unsafe.Pointer(buffer))
+	return str
+}
+
+func ConvertAndFreeCoTaskMemBytes(buffer *uint16) []byte {
+	return []byte(ConvertAndFreeCoTaskMemString(buffer))
+}
+
+func Win32FromHresult(hr uintptr) syscall.Errno {
+	if hr&0x1fff0000 == 0x00070000 {
+		return syscall.Errno(hr & 0xffff)
+	}
+	return syscall.Errno(hr)
+}